Question

select the correct answer from the drop-down menu.
people keep spending additional units of a particular resource on a want until their marginal benefit is their marginal cost.

Explanation:

In economics, the principle of marginal analysis states that people will continue to allocate resources to a want as long as the marginal benefit (the additional benefit from one more unit) is at least equal to the marginal cost (the additional cost from one more unit). Typically, the optimal point is where marginal benefit equals marginal cost, as beyond that, the cost of an additional unit would exceed the benefit, so people stop at the point where they are equal (or when benefit is no longer greater than cost, but the key equilibrium is when $MB = MC$). So the correct relationship here is that people keep spending until marginal benefit is equal to marginal cost.

Answer:

equal to