John Raises Bees to Pollinate His Orchard

Multiple Choice

John raises bees to pollinate his orchard. A couple of bees which escaped ended up pollinating his neighbor's orchard, so

A) John's neighbor has received an internal cost of John's bee-keeping.
B) John's neighbor has received an external cost of John's bee-keeping.
C) John's neighbor has received an external benefit of John's bee-keeping.
D) None of the above is correct.