Which of the following is not an example of an operational d

Which of the following is not an example of an operational definition?

a. great grandpa\'s recipe for moonshine

b. an actor has memorized his lines when he can repeat all of his lines twice without an error

c. reaction time is the interval between the presentation of a stimulus and the participant\'s response

d. a rat is hungry when the rat craves food

Solution

a. great grandpa\'s recipe for moonshine