The standard error of the mean may never be negative

According to research on the tip-of-the-tongue phenomenon,

a. when an item is on the tip of your tongue, you will seldom be able to recover it. b. your mental dictionary is arranged in alphabetical order. c. you can identify similar-sounding words, but you cannot accurately guess the number of syllables in the target word. d. you can typically provide a similar-sounding word, which matches the target word reasonably closely.

Because most heroin addicted people prescribed naltrexone stop taking it,

A. it is no longer used for this purpose. B. they typically undergo prolonged withdrawal reactions. C. researchers are testing a depot form that blocks heroin's effects for up to six weeks. D. a company is developing a better tasting capsule.