Question

what is a confounding variable?
a confounding variable is a variable other than the explanatory variable that causes a change in the response variable during the study.
a confounding variable is a variable that does not cause either the explanatory or response variable to change during the study.
a confounding variable is a variable other than the response variable that causes a change in the explanatory variable during the study.
a confounding variable is a variable that causes both the explanatory and response variable to change during the study.

Explanation:

A confounding variable is an extraneous variable that is associated with both the explanatory (independent) and response (dependent) variables, distorting the true relationship between them by causing changes in both.

Answer:

A confounding variable is a variable that causes both the explanatory and response variable to change during the study.