Dr. Samson wanted to know how college students in his state would vote during the next election. By sampling the seniors at his college, he can get a representative sample

Development of male genitals before birth is largely due to the presence of

a. two X chromosomes. b. testosterone. c. estrogens. d. the bulbo-urethral gland.

Many factors work together in motor development, according to

a. dynamic systems theory. b. working memory. c. learning theory. d. the developmental cascade.