Parallel questions have a highly regimented theory and approach – even if your core logical intuitions are very strong, following a routine process specifically built around the LSAT’s unique patterns will dramatically reduce the time and mental energy required to identify the correct answer. So review these lessons. They’re important.

In short, though, our approach will be to develop an abstract model of the stimulus’ argument, preserving the structure but not the subject matter, then take a shallow dip into the answer choices looking for structural mismatches. Usually that suffices to identify the correct answer, but sometimes we’ll need a deep dive to distinguish between the (usually just two) answer choices that remain after our shallow dip

If thinking about this question in English is easier for you than using formal logic, you need more practice gaining fluency in formal logic. Think of English and formal logic as two closely-related tools, like a hand screwdriver and a power screwdriver. While it’s true that any job you can complete with one you could also complete with the other, they each have niche uses in which they excel. If you find yourself tackling a line of 100 wood screws with a hand screwdriver, you need to get better with the power screwdriver.

Before diving into the full explanation, I’ll just note that a “thinking in English” approach to this question narrows us down to (A) and (C) without requiring too much advanced knowledge. Perhaps the most realistic approach from a high scorer would be to recognize the “some before all” structure, eliminate answers (B), (D), and (E) on a shallow dip, then loop back to diagram the stimulus upon realizing how closely (A) and (C) resemble it.

Anywho, here’s a walkthrough of all the skills you need to reach the correct argument structure. Starting with the first sentence, which is just a straightforward some claim:

Premise 1: Tarantula ←some→ Good Pet

Interpreting the second sentence correctly means remembering that “no” negates the necessary condition:

Premise 2: Poison Fangs → /Good Pet

Diagramming the conclusion correctly is also a bit tricky – you need to remember that “not all” translates to “some aren’t”:

Conclusion: Tarantula ←some→ /Poison Fangs

So we’ve got one “some” premise, one “all” premise, and a “some” conclusion. We’re also in a normal Parallel question, not a Parallel Flaw question. That’s enough to suspect we’re probably working with a some before all argument structure: if we took the time to figure it all out, the correct diagram would probably match that template, resulting in a valid argument. As mentioned earlier, that’s enough information for a shallow dip. But choosing between (A) and (C) requires a deeper dive, so on with the diagramming we go!

First, here’s the abstract “some before all” structure:

Premise 1: A ←some→ B
Premise 2: B → C
________
Conclusion: A ←some→ C

And here it is again with the premises chained up:

Premise: A ←some→ B → C
________
Conclusion: A ←some→ C

Now here are the three claims from the stimulus:

Premise 1: Tarantula ←some→ Good Pet
Premise 2: Poison Fangs → /Good Pet
________
Conclusion: Tarantula ←some→ /Poison Fangs

Cleanly linking the “some” claim to the “all” claim involves taking the contrapositive of Premise 2:

Premise 2: Poison Fangs → /Good Pet
Premise 2 (CP): Good Pet → /Poison Fangs

Here are the three claims again, with the resulting conditional chain:

Premise 1: Tarantula ←some→ Good Pet
Premise 2 (CP): Good Pet → /Poison Fangs
________
Conclusion: Tarantula ←some→ /Poison Fangs

And here it is again with the premises chained up:

Premise: Tarantula ←some→ Good Pet → /Poison Fangs
________
Conclusion: Tarantula ←some→ /Poison Fangs

So the stimulus does indeed follow the “some before all” structure. That’s the template (A) and (C) are trying to match.