When Doing a Computerized Search for Quantitative Studies on a Topic

When doing a computerized search for quantitative studies on a topic, which of the following statements is most accurate?

A) The best place to begin is to use a search engine such as Yahoo or Google
B) The primary keyword to use in the search typically would be the population
C) The keywords to start the search typically would be the independent and dependent variables
D) The specific subject headings used in each bibliographic database would have to be learned