Please help with this exam

What is the relationship between marginal external cost, marginal social cost, and marginal private cost? a. marginal social cost equals marginal private cost plus marginal external cost. b. marginal private cost plus marginal social cost equals marginal external cost. c. marginal social cost plus marginal external cost equals marginal private cost. d. marginal external cost equals marginal private cost minus marginal social cost. marginal external cost a. is expressed in dollars, so it is not an opportunity cost b. is an opportunity cost borne by someone other than the producer c. is equal to two times the marginal private cost d. is a convenient economics concept that is not real

Uknow what i love about i ask a dumb question it is immediately answered but when i ask a real question it take like an hour to get answered

On september 1, 2016, steve loaned brett $2,000 at 12% interest compounded annually. steve is not in the business of lending money. the note stated that principal and interest would be due on august 31, 2018. in 2018, steve received $2,508.80 ($2,000 principal and $508.80 interest). steve uses the cash method of accounting. what amount must steve include in income on his income tax return?