You Read in a Psychology Journal That the Authors of an Article

You read in a psychology journal that the authors of an article have conducted a meta-analysis. You conclude that they have

A) analyzed the variety of independent variables that would probably influence the dependent variable they are studying.
B) conducted a study with at least 100 participants.
C) located previous studies on a topic and then statistically combined the results of those studies in order to determine an overall effect.
D) interviewed at least 20 experts in the appropriate field and compared their opinions on a particular topic.