Before the end of the first month of embryonic development, the neural tube is producing about 400 million neurons per

Watching his grandchildren for the weekend has increased the environmental press in Hugo's life slightly, bringing out the best in Hugo's interpersonal skills. While watching his grandchildren, Hugo is apparently operating a. at the adaptation level

b. in the zone of maximum comfort. c. in the zone of maximum performance potential. d. in a marginal zone.

The primary cause of death in the United States today is

a. accidents. b. old age. c. cardiovascular disease. d. pneumonia. e. AIDS.