Although you are really tired after a long run, you are considering meeting a friend at the local track to run a few more miles. You will choose to keep running if Choose one: A. the marginal benefit of meeting a friend at the local track to run a few more miles exactly equals the marginal cost. B. meeting a friend at the local track to run a few more miles is free, so the marginal cost is zero. C. meeting a friend at the local track to run a few more miles is guaranteed to be fun, so the marginal benefit is high. D. the marginal benefit of meeting a friend at the local track to run a few more miles outweighs the marginal cost.