Refer to Exhibit 31-2. This graph represents a positive externality situation. Given this, which of the two curves, X or Y, represents marginal social benefits and why? Group of answer choices Curve X, because if there is a positive externality, negative external benefits are associated with it: social costs external benefits - private benefits, therefore the marginal social benefit curve must lie below the marginal private benefit curve. Curve X, because if there is a positive externality, external benefits are associated with it: social benefits = external benefits + private benefits, therefore the marginal social benefit curve must lie below the marginal private benefit curve. Curve Y, because if there is a positive externality, external costs are associated with it: social benefits = external costs + private benefits, therefore the marginal social benefit curve must lie above the marginal private benefit cost curve. Curve Y, because if there is a positive externality, external benefits are associated with it: social benefits = external benefits + private benefits, therefore the marginal social benefit curve must lie above the marginal private benefit curve