John just ate a big Thanksgiving dinner. When John is offered a piece of his favorite pie he declines. The decrease in the reinforcing value of pie for John is an example of:

Which of the following issues are teenagers most likely to argue with their parents about?

A) drug use B) sexual activity C) religion D) household chores

What percent of individuals older than 65 years in developed countries have at least one grandchild who is at least 18 years old?

a. 30% b. 40% c. 50% d. 60%