Which of the following is NOT an example of business-to-business marketing?

A) Scott Sign Systems sells interior signs to an Alabama resort.
B) A municipal government buys chemicals for its city swimming pools.
C) Sue buys a gift for her mother.
D) A Canadian software company buys airline tickets to send a group of salespeople to make a presentation to a heavy equipment manufacturer in Japan.
E) Airmark sells a vinyl printing press to a manufacturer of plastic bags.

C