The capacity to use __________ as a flexible symbolic tool improves from the end of the second into the third year

What happens when the amount of oxytocin in a human female's blood reaches a certain threshold?

a. The likelihood of conception is at its highest. b. The process of birth begins. c. Labor pains are decreased considerably. d. Lactation begins.

Color blindness is an example of X-linked inheritance. The gene for color blindness is located on the X chromosome. It is more likely to occur

a. in females because they have two X chromosomes. b. in females because the effects of any genetic disorder are stronger for them. c. in males because the Y chromosome does not have a corresponding allele to counteract the color blindness allele on the X chromosome. d. in males because the effects of any genetic disorder are stronger for them.