Questions: 3. What does it mean to manipulate a variable? a. to hold extraneous variables constant b. to turn a potential cause on and off c. to measure the variable's effect on behavior d. to hold the potential cause constant

The answer is B: to turn a potential cause on and off.

Explanation for each option:

a. To hold extraneous variables constant: This refers to controlling other variables that might influence the outcome of an experiment, ensuring that they do not affect the results. This is not the same as manipulating a variable.

b. To turn a potential cause on and off: This is the correct answer. Manipulating a variable means deliberately changing it to observe the effect of these changes on another variable. For example, in an experiment to test the effect of light on plant growth, the amount of light is manipulated (turned on and off or varied in intensity) to see how it affects the growth of the plants.

c. To measure the variable's effect on behavior: This describes the process of measuring the outcome or dependent variable, not the manipulation of the independent variable itself.

d. To hold the potential cause constant: This would mean keeping the variable unchanged, which is the opposite of manipulation. Manipulation involves changing the variable to see its effects.

In summary, manipulating a variable involves actively changing it to study its effects on another variable, which is best described by option B.