Dozens of cars passed by before Jack got help when stranded on a busy road. Mike got help from the first person to pass by when he had car trouble on an almost deserted road. The difference in helping behavior they encountered is most consistent with:

Using parabiotic mice to investigate genetic influences on obesity, it was found that:

a. If db/db mice were paired with normal mice, the normal mice starved. b. If db/db mice were paired with ob/ob mice, the ob/ob mice starved. c. Paired ob/ob mice with normal mice slowed the weight gain of ob/ob mice. d. All of the above are true.

Research into early visual perception has indicated that:

a. newborn vision is nearly identical to the 20/20 vision of adults b. newborn vision is very clear, and newborns can perceive fine details better than most adults c. newborns have good black and white vision at birth, but poor color vision d. newborn vision is very blurry