Which of the following would be considered real property?

A: A maturing grape crop which is under a sales contract and to be harvested later;
B: Trade fixtures that a tenant has installed but which are removable without damage;
C: A built-in refrigerator in a mobile home that is not attached to a permanent foundation;
D: A bearing wall in a single-family house.

Answer: D: A bearing wall in a single-family house.