Aresearcher conducts an experiment to see which type of therapy is most successful in identifying marital problems. in this situation, the experiment is a part of the step of the scientific method.

This experiment is part of the step called "experimentation".

Explanation:

Experimentation is the stage of the scientific method where the researched can perform different tests and procedures that will test the veracity of the hypotheses raised for that study.

In relation to the question above, we can see that the researcher is testing different types of therapy in order to determine which one is more appropriate in identifying marital problems, so we can say that the researcher is in the experimentation stage.