Dr. steinguard wants to demonstrate a cause-and-effect relationship between stress and memory. which of the following research methods should he use?
a. correlational studies
b. survey method
c. naturalistic observation
d. experimental method

Experimental method

Explanation:

The first method of inquiry in science is an experiment. It is the main feature is to control the variables. It is used to measure and establish a good relationship between the cause and effect method. It will advantageous if the method will be advantageous. It is a scientific method in which the hypothesis is measure in an in a scientific way. In this method, the independent method is manipulated and the dependent variable is measured. The experiment method should be objective. This method makes the data less biased and more valid.  

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.

answer; mental health prevention programs;