Why Are Convenience Samples Used So Frequently in Nursing Research

Why are convenience samples used so frequently in nursing research, when a random sample would allow for greater generalizability?

A) Convenience sampling allows researchers to select not only subsets but qualities associated with them.
B) Key informants are desired.
C) Random sampling is really not an issue, since little nursing research is replicated.
D) Potential subjects often are reluctant to consent for in-hospital research.
E) Nurses are limited to the populations they serve; many populations are small and difficult to access.