Was this experimental or post-facto research?

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.

A disadvantage of open-ended questions is that

a. they provide limited scope for response. b. answers may be difficult to categorize. c. they reflect the researcher's point of view. d. none of these