Jodie is studying the sleeping habits of various types of animals. She wants to know how long each type of animal sleeps during the day. Jodie puts each of the animals in a cage with food, water, and light. However, she cannot stay to watch the animals all day.

Which of the following tools would be most helpful to Jodie's experiment?
A.
a tape recorder
B.
a video camera
C.
a metric ruler
D.
a triple beam balance