Frequency theory was originally called the _____ theory

What is the five-year divorce rate for American couples in which both partners have four-year college degrees?

a. 6% b. 13% c. 20% d. 27%

Which of the following is not included in the category of "monoamine" neurotransmitters?

a. serotonin b. norepinephrine c. dopamine d. endorphins