On which axis of a DSM-IV-TR diagnosis is mental retardation listed?

Which statement BEST reflects the relationship between serotonin and suicide?

A) Low levels of serotonin are related to high levels of aggression and impulsivity. B) High levels of serotonin are related to high levels of aggression and impulsivity. C) Serotonin makes people more likely to abuse substances, increasing the likelihood of their committing suicide. D) Suicide attempts increase the level of serotonin in the brain, making suicide more likely.

If psychologists give a test twice in order to determine whether the scores change, theyare

attempting to measure the ________ of the test. A) validity B) accuracy C) reliability D) operational definition