The Case Study Method Is One in Which ________

The case study method is one in which ________.

A) specially constructed tests are administered to reveal subjects' abilities, skills, career interests, or mental health
B) researchers manipulate one or several variables while controlling all other variables to measure the impact of the changing variable(s) on subjects and their behaviors
C) findings are based on the naturally occurring relationships between two or more variables
D) findings are based on the intensive description and analysis of a single individual or a few individuals