When one can alternately see both a wine glass and then two faces within the same image, this illustrates the reversibility of images

Dr. Wiseman wants to know about the alcohol consumption patterns among college juniors in the United States. He should __________

a) give the survey to every college junior in the country. b) remember that sample size is the most critical factor in survey research. c) require students' names on each survey to avoid the tendency to lie. d) draw a representative sample among college juniors.

Because critics have argued that these procedures are unnecessary, they have decreased from 90% in 1970 to 20% in 2000

a. crownings b. episiotomies c. vaginalectomies d. amniocenteses