Normal development of male external genitalia requires the direct action of

a. 5-alpha-dihydrotestosterone.
b. testosterone

Which of the following people fits the typical pattern for someone who quits smoking?

a) Sonny, who has tried to quit smoking numerous times without success but finally quits on his own after the death of his father from lung cancer. b) Marilyn, who quit "cold turkey" on her very first attempt to stop smoking. c) Pat, who went to individual and group counseling to quit smoking after an unsuccessful first attempt. d) Vonie, who quit smoking on her first attempt by using a combination of nicotine gum and patches.

In a(n) __________ design, researchers look at relationships between participants' characteristics and their behavior or development

A) observational B) correlational C) experimental D) variable