Self-study
Studies have shown that Support those who take daily doses of vitamin C are less likely to contract colds than are those who do not. █████ ██ █ ██████ █████████ █ █████ ██ ██ ███ ████████ ████ ███ ████ █████ █████ ██ ███████ ██
Method of Reasoning
The argument cites a negative correlation between two things (taking vitamin C makes contracting colds less likely), then concludes that if one thing has happened (contracting a cold), the other probably hasn't happened (probably no vitamin C).
The Flaw
This argument assumes that because vitamin C users are less likely to catch colds, anyone who catches a cold probably doesn’t take vitamin C. However, it never establishes the relative sizes of the groups involved. If nearly everyone takes vitamin C, then even if it reduces one’s chances of catching a cold, most people who get colds could still be vitamin C users.
11.
The questionable reasoning in the ████████ █████ ████ ███████ █████████ ████ ██ █████ ███ ██ ███ ██████████
a
To be classified ██ █ ██████████ █ ████████ █████ ██ ███ ████████ █████ ████ ████ █████████ ████ ██████ ██ ████ ██ █████ ████ ███████████ ███ █████ ██ ████████ ██████ ████ █████████ ████ ██████ ██ █████ ████ █████ ███ ███ ███████████
You should eliminate (A) after reading its first sentence, which lays out a firm "if, then" relationship rather than a correlation between two groups.
b
Everyone who ate ███ ████ █████ ████████ ██ ███ █████████ ███ ██████████ █████████ ██ █████ ███ ███ █████ ██████ ████████ ██ ███ █████████ ████ ████████ ████ ███ ████ ████████
(B)'s first word (everyone) should be suspicious as a quantifier mismatch with the stimulus. That is, the stimulus doesn't say "everyone who takes daily doses of vitamin C is immune to colds."
(B)'s mention of other dishes also departs from the stimulus, which never strays from the relationship between vitamin C and colds.
c
Laboratory rats given ██ █████████ ███████████ ████ ████ ██ ██ ██ ███████ ██████ ████ ██ █████ █████ █ ████ ████████ █████ ██ ████ ██████ █████ ██████ █████ ████ █████ ██ ██████ █ █████ ████ ████ ████ ████ ███████ ███
(C) features a different flaw (what's true for rats doesn't necessarily extend to humans), which should be a strong signal to eliminate it.
d
People who train ██████████ ██ ████ █████ ███ ███████ █ ███████ █████ ██ ████████████ ██ █████ ███████ ███ █████ ███████ ██ ████ ████ ██████
(D) features a different flaw. It assumes that because one cause can produce an effect (diligent training can enable proficiency at poker), no other causes could possibly contribute to that effect (hard work alone).
e
Automobile engines that ███████ ███████ ███ ███████ ███ ████ ██████ ██ ██ ███████ ████ ████ ███ █████ ████ ██ ████ ██ ███████████ ████ ██████ ████████ ████████ ████ ███ ███ ███████ ███ ████████
Like the stimulus, (E) cites a negative correlation between two things (oil changes makes engine problems less likely), then concludes that if one thing has happened (engine problems), the other probably hasn't happened (probably no oil changes).