Answer:
D.
Step-by-step explanation:
Experimental research is research that is always done in an controlled environment. The people setting this experiment up want that controlled environment because they're not really experimenting with something. The point of it is to prove a point, or confirm information that is already known, like something you would do in a science lab at school. You make a hypothesis, the researcher manipulates the variables, measures the outcome, and compares the results.
These are often artificial, and subject to error by the participants, so the results are often very subjective and unrealistic.