Treatment for heroin addiction often involves

Which classification of mental retardation affects most of the population classified in this fashion?

a) mild b) moderate c) severe d) profound

Tina is a master runner. If she practices consistently throughout her life, she can expect her performance speed to

A) significantly drop in her late twenties, followed by a steady decline into her sixties. B) drop only slightly from the mid-thirties into the sixties, when it will fall off at an accelerating pace. C) significantly drop each decade from the mid-twenties to the late sixties or early seventies. D) increase through her mid-forties, when it will fall off at an accelerating pace.