Which of the following is included in the calculated Gross Domestic Product?

a) Farmer Freddie sells his second tractor to his son.

b) Suzanne buys a love seat and chair for $85 at the yard sale on the corner.

c) A local ice cream store sells $17,000 worth of cones and sundaes on July 1.

d) Mr. Farkle buys a used lawn mower from his neighbor, Mr. Sparkle.