Final answer:
The answer to the question of which option is a variable expense is Groceries, as the cost can fluctuate based on consumption, unlike the other listed fixed expenses.
Step-by-step explanation:
The student has asked which of the following is a variable expense:
- Rent on an apartment
- Groceries
- A gym membership
- A car payment
Among these options, the correct answer is Groceries. Variable expenses are costs that can vary depending on your use of products or services; they are not fixed. For example, the amount of money you spend on groceries each month can change based on how much you consume, whereas rent on an apartment, a gym membership, and a car payment are typically consistent payments each month.