Which of the following research findings, if true, would provide the strongest evidence of the influence of genes on intelligence?

A. Survey persons over the age of 55: This is a correlational survey design; it can identify associations between exercise and cognition but cannot establish causation because of possible confounds and lack of experimental control.
B. Compare residents of active vs non-active retirement communities: This is a quasi-experimental / naturalistic comparison; it’s stronger than a simple survey but still vulnerable to selection effects and other confounds (not true random assignment).
C. Randomly assign adults to exercise or sedentary activity and test pre/post: This is a true experimental design (random assignment + control) with pre/post measures, which is the method required to infer cause-and-effect.
D. Case study of a 60-year-old competitive weightlifter: A single case study provides rich detail but has no generalizability and cannot demonstrate causation.
E. Compare a biking club to a book discussion group: This is an observational/comparative design subject to self-selection bias (active people join biking clubs), so it shows association but not causation.

A. Authoritarian: Authoritarian parenting is high control/low warmth; children often are obedient or may become rebellious but not typically described as simply immature and lacking self-control due to permissiveness.
B. Authoritative: Authoritative parents combine warmth and consistent limits; their children usually show good self-control and social competence.
C. Permissive: permissive (indulgent) parenting is low in firm limits and discipline, often producing children who are impulsive, immature, and have poor self-control.
D. Neglectful: Neglectful (uninvolved) parenting leads to many problems (attachment, academic), but the vignette emphasizes immaturity and refusal to listen-classic for permissive.
E. Rejecting: “Rejecting” is similar to neglectful/uninvolved; it implies emotional rejection rather than the indulgent permissiveness described.