When the marginal benefit to cost is equal between two options like exactly equal do you switch from option A to

Question

When the marginal benefit to cost is equal between two options, like exactly equal, do you switch from option A to

Option B after counting that option A, or do you count option B first. Like, If you have one option A then option B. When they both eventually equal the same value per marginal dollar, would you say that the maximized value of A over B is when the two balance or after b surpasses a (counting option a first).

Economics