Question

what helps a consumer determine the quantity of something to buy?
marginal cost
marginal error
marginal benefit
marginal comparison

Explanation:

To determine the quantity to buy, a consumer considers the additional benefit (marginal benefit) from each unit. Marginal cost is about production costs, marginal error is not relevant to consumption decisions, and marginal comparison is not a standard term for this. So marginal benefit helps assess if the gain from buying another unit is worth it.

Answer:

C. marginal benefit