Question

in a 2002 study, psychologist avshalom caspi and his colleagues investigated how genetic and environmental factors interact to influence antisocial behavior. the researchers hypothesized that individuals with a low-activity variant of the monoamine oxidase a (maoa) gene—often associated with impaired regulation of neurotransmitters like serotonin and dopamine—would be more likely to exhibit antisocial behavior, but only if they had also experienced childhood maltreatment. to test this, the team analyzed longitudinal data from over 1,000 males in new zealand, tracking genetic profiles alongside self - reported and observed measures of maltreatment and behavioral outcomes. their findings confirmed the interaction: those with both the low - activity maoa genotype and a history of abuse were significantly more likely to engage in violent or criminal behavior later in life, compared to those with only one or neither of those factors.
5
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which choice best describes the underlined portion of the text?
a it qualifies a causal relationship by introducing a second variable that is always present when a behavior occurs.
b it introduces the environmental condition necessary for the genetic factor to significantly influence certain physical traits.
c it narrows the scope of the hypothesis by specifying a condition under which the proposed outcome becomes relevant.
d it emphasizes that childhood maltreatment has a stronger influence on behavior than genetic makeup alone.

Explanation:

1. Analyze Option A: The underlined part is about a condition (childhood maltreatment) for the genetic factor (low - activity MAOA gene) to influence antisocial behavior, not a variable always present with the behavior. Eliminate A.
2. Analyze Option B: The outcome is antisocial behavior (a behavioral trait), not a physical trait. Eliminate B.
3. Analyze Option C: The hypothesis is that individuals with the low - activity MAOA gene are more likely to exhibit antisocial behavior. The underlined part “but only if they had also experienced childhood maltreatment” specifies the condition (childhood maltreatment) under which the proposed outcome (more likely to exhibit antisocial behavior) becomes relevant. This narrows the scope of the hypothesis.
4. Analyze Option D: The text is about the interaction of genetic and environmental factors, not about childhood maltreatment being stronger than genetic makeup alone. Eliminate D.

Answer:

C. It narrows the scope of the hypothesis by specifying a condition under which the proposed outcome becomes relevant.