Psychologists use the concept of motivation as a(n) variable to find the unity beneath the apparent diversity of many human behaviors.

a. ameliorating
b. moderating
c. explanatory
d. differential
e. intervening

e. intervening              

Explanation:

Intervening variable: The term "intervening variable" is defined as a hypothetical variable that is being used to describe the causal relationship between other different types of variable. It can't be observed during an experiment because of its hypothetical nature. It is being utilized to explain the relationship between dependent variables and independent variables.

Example: A connection between being rich and having a broader perspective in life.

In the question above, the statement signifies the intervening variable.

answer; adoption agencies tend to place separated twins in similar homes;