In terms of the scientific method, the purpose of an experiment is to:
D) Test a hypothesis
After forming a hypothesis, you TEST it out by performing the experiment and collecting data. After collecting the data from the experiment, you can form a conclusion about the results of the experiment.
An experiment is supposed to tell you whether the hypothesis you came up with is true and is able to be proven with an experiment.
The purpose of an experiment is to test a hypothesis and see whether the results you get support or contradict your hypothesis.