Which of the following are included in this year's GDP? Explain your answer in each case.

a. An auto dealer's sale of a new car to a non-business customer.

b. The services of a commercial painter in painting the family home.

c. The money received by Smith when she sells her biology textbook to a used-book buyer.

d. A $2 billion increase in business inventories.

e. The publication and sale of a new economics textbook.

f. Government purchases of newly produced aircraft.