In the context of gathering primary data through survey research, which of the following is a disadvantage of telephone interviews?
a. The cost of telephone interviews increases when respondents refuse to participate.
b. The federal "Do Not Call" law applies to survey research.
c. Central-location telephone facility used in the interviews consume a lot of time.
d. Multiple locations need to be used when interviewing people nationwide.
Answer: a. The cost of telephone interviews increases when respondents refuse to participate.