Suppose that John allocates $10,000 of his disposable income for necessities. Any additional income beyond that is both spent and saved. Assume that he has an annual disposable income of $50,000 and MPC = 0.8. Based on this information, the amount of money John should save would be: A. $10,000. B. $40,000. C. $12,000. D. $8,000.