One Day While Ted Was Cleaning His Aquarium, He Noticed

One day while Ted was cleaning his aquarium, he noticed the heater was still plugged in. He reached down with a wet hand and tried to unplug the cord. As a result, Ted received a shock. After that experience, Ted has never attempted to unplug an electrical cord with a wet hand. The effect the shock had on Ted's behavior is known as

A) negative reinforcement.
B) positive punishment.
C) positive reinforcement.
D) penalty (or negative punishment) .