Answer:
The correct answer is option C.
Step-by-step explanation:
The utility from consuming two candy bars is 20 units.
The utility from consuming three candy bars is 25 units.
The marginal utility of the third candy bar will be the increase in the utility on consuming additional unit of candy bar.
It can be calculated by the utility derived from consuming three bars minus the utility derived from consuming two bars.
Marginal utility of third candy bar
=25 units - 20 units
=5 units
So, the correct answer is 5 units.