Miguel is a 20 year old college student who works part-time and earns an annual income of $12,000. To smooth out his life cycle changes in income, Miguel can
A. attempt to pay for college from his current earnings.
B. borrow money to pay for college, which he will later repay when his income rises.
C. lend money to a friend to purchase a new car.
D. save his earnings to use when he is middle-aged.