Logical reasoning PrepTest 109 · Section 1 · Question 1

Incorrect. First, if anything, this would call the conclusion into question since these right—handed adult marmosets should lead kids to be right—handed. Second, the stimulus already noted that there were some marmosets who were right—handed, so this answer doesn't even weaken the argument.

Incorrect. This answer throws a wrench in the works—if siblings have different handedness, then it's unclear where it comes from! They presumably have similar genetics and similar adults to imitate, so this answer doesn't support one explanation over another.

Incorrect. This doesn't speak at all to where these marmosets learn the skill from.

Incorrect. This answer would require us to know that marmosets and humans are similar in their causes of handedness. Since we know that marmosets and humans are different in a key respect here (the former is predominantly left—handed; the latter right—handed) that's not a good assumption.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen

Stimulus Summary:
Phenomenon — Marmosets are mostly left—handed
Explanation/Hypothesis — Baby marmosets mimic adult marmosets, so they learn left—handedness

Answer Anticipation:
Hypotheses are generally explanations for observed phenomena, and this one is no different. It has been observed that marmosets are mostly left—handed, and the explanation/hypothesis presented in the stimulus is that they "learn" this from the adults who are mostly left—handed. (There's a little bit of a chicken/egg problem there . . . )

Hypotheses are generally causal as they mostly explain what causes the phenomenon. Here the supposed cause is the babies mimicking the adults with the effect being the predominance of left—handedness. And picking one explanation generally ignores others. As such we can anticipate answer choices related to these flaws:
(1) Eliminate alternative causes/explanations
(2) More examples of cause and effect going together
(3) A control — no cause no effect

Answer Explanation:
This answer does two things to strengthen the argument. First it suggests that it's not genetics that determine handedness since the "adopted" marmosets take on the characteristics of their adoptive parents. Second it provides examples that break with the overall trend while aligning with the hypothesis—by showing "same cause same effect." Here imitation of adults was the cause of handedness and we see that panning out even among a population that breaks the overall trend in the population!

Key Takeaway:
Passages that include a hypothesis will almost always fall into the phenomenon/explanation pattern which means that they're usually flawed in ignoring other potential explanations. Hypotheses are also almost always causal so we can use what we know about arguments with causal flaws in these questions as well.