Which of the Following Is a Definition of Experimental Research

Multiple Choice

Which of the following is a definition of experimental research?

A) research strategy that allows the precise conclusion of how strongly two factors are related to each other
B) method of study that involves an intensive, in-depth investigation of a single individual or small group of individuals
C) systematic observation and recording of behaviors as they occur in their natural setting
D) research method used to determine a cause-and-effect relationship between changes in one variable and the effect that is produced on another variable