Which of the following is the best example of the learning principle of reinforcement?

A) Sammy’s father stopped buying him candy when Sammy cried, and Sammy stopped crying for candy for a while. However, one day Sammy randomly started crying for candy again.
B) Coraline trained her cats to respond in different ways to two different whistle pitches. They would come to be fed when she blew one whistle and leave when she blew the other whistle so she could clean their litter boxes.
C) Five-year-old Mandy learned to write with a pencil, but she can also write with a marker, a crayon, or a pen.
D) Marla audited a class, so she never took any quizzes or tests throughout the year. However, she decided she wanted to take the end-of-year final and received a very high grade without taking earlier exams.
E) James drank coffee before he took and passed a difficult test with a high grade, so now he drinks coffee before every test he takes because he believes doing so will help him score well on the tests.

Answer: E) James drank coffee before he took and passed a difficult test with a high grade, so now he drinks coffee before every test he takes because he believes doing so will help him score well on the tests.