(A) should fail your shallow dip because it’s missing an entire premise. It’s a great example of flawed reasoning that follows the percent vs. amount pattern.

(In fact, take a moment to articulate the objection to this reasoning. It’s good practice.)

We’ve got a premise about the number of tubs and a conclusion about the percentage of tubs, but we’re missing the premise about the number of apartments.

(B) matches the stimulus’ reasoning point-for-point.

The first premise is about the top number (# of tubs). It says the number of tubs in Modern apartments is lower than the number of tubs in Victorian apartments.

The second premise is about the bottom number (# of apartments). It says the number of Modern apartments is higher than the number of Victorian* apartments.

The conclusion is about the percentage of apartments that have tubs. It says the percentage of Modern apartments with tubs is lower than the percentage of Victorian apartments with tubs.

Here’s a full diagram, with info from premise 1 in pink and info from premise 2 in green:

This conclusion is valid. The Modern percent comes from dividing a small number by a big number, and the Victorian percent comes from dividing a big number by a small number. The Victorian percent is bigger.

*But what about the jump from large Victorian apartments in premise 1 to just Victorian apartments in premise 2? Two points on that.

First, the stimulus does the same thing, jumping from full-length Sci-Fi in premise 1 to just Sci-Fi in premise 2. So (B) at least matches up.

Second, although this is indeed a jump between different concepts, it’s a jump from a subset to a superset, which doesn’t interfere with the reasoning in this case because the premise we’re given implies the premise we want. That is:

If there are more Short Docs than there are Sci-Fi films of any kind, then there are more Short Docs than the subset of full length Sci-Fi films.

If there are more Modern apartments than there are Victorian apartments of any kind, then there are more Modern apartments than the subset of large Victorian apartments.

It’s subtle, but (C) should die on your shallow dip because (C)’s first sentence is its conclusion, as indicated by the word for in the second sentence.

Everything else matches up, so catching this straight away is critical not just to get the question right, but also to avoid the time sink of comparing (B) and (C) – and (D), by the way – in detail.

You really should aspire to be so keyed in to premise and conclusion indicators that you catch the “for” thing during your shallow dip. If you didn’t, I highly recommend you go back and do some more premise and conclusion drills.

Not even because you’re necessarily bad at telling premises and conclusions apart – you’re probably pretty good at it when you know that’s the game you’re playing. Really the skill to practice is constant vigilance. It’s continual attunement to this foundational LSAT concept, which is so often the difference-maker between right and wrong answers.

(D) should die on your shallow dip because (D)’s second claim is its conclusion, as indicated by the word so at the beginning of the second clause and the word since at the beginning of the third clause.

Everything else matches up, so catching this straight away is critical not just to get the question right, but also to avoid the time sink of comparing (D) and (B) and (C) in detail.

You really should aspire to be so keyed in to premise and conclusion indicators that you catch the “so” thing during your shallow dip. If you didn’t, I highly recommend you go back and do some more premise and conclusion drills.

Not even because you’re necessarily bad at telling premises and conclusions apart – you’re probably pretty good at it when you know that’s the game you’re playing. Really the skill to practice is constant vigilance. It’s continual attunement to this foundational LSAT concept, which is so often the difference-maker between right and wrong answers.

(E) is wrong because the “bigger than” and “smaller than” relationships don’t pencil:

The Modern tubs # is smaller than the Victorian tubs #.

The Modern apartments # is also smaller than the Victorian apartments #.

This makes the percent comparison inconclusive. When you’re dividing a small number by a small number, that’s not necessarily bigger or smaller than dividing a big number by a big number. Behold this mathematical proof:

$\frac{1}{2}=\frac{2}{4}=\frac{600}{1200}$