Last year, Sandra had rented a house in Dallas at $4,000 per month, which was the going market rate at the time. The rental rates in Dallas this year have not changed from last year and Sandra wanted to renew her lease. But, the owner of the house decided to sell it. Sandra liked the house and ended up buying it. So, this year instead of a rent, she is making a monthly payment of $4,500 on his mortgage. For simplicity, assume that the cost of the real estate transaction was $0. As a result of this change in ownership, the monthly contribution of the house to the real GDP of the United States has:

A.declined by $4,000.

B.declined by $500.

C.not changed

D.increased by $500.

E.increased by $4,000

F.increased by $4,500.