What's the main reason that the sex ratio is usually below 100? a. on average, men live longer than women. b. on average, women live longer than men. c. men are more likely to die in infancy. d. one hundred percent is a logical limit.

What was piaget's explanation as to why preschool-age children in the preoperational stage make errors on tasks requiring conservation? a) preschool children's tendency toward centration prevents them from focusing on other relevant features of a situation b) preschool children have not yet developed numerical understanding; therefore, different amounts are meaningless c) preschool children's neural-visual network is not fully matured d) preschool children have not lived long enough and accrued enough experience to know the difference between quantities