The answer is
A) desensitization
According to the context that is described a group of volunteers were shown a movie in which innocent victims are killed.The volunteers were scared and shocked after watching the movie for the first time, but started cracking jokes and making rude comments when they were shown the movie repeated number of times.In this context it is clearly shown that after the movie was shown repeated number of times to the volunteers, their emotional responses ( scared and shocked in this context) reduced or diminished. This illustrates desensitization. The term desensitization is proposed my Mary Cover Jones. Desensitization is used as a treatment to reduce phobias and anxieties towards any stimuli ( positive or negative). Desensitization is a process in which emotional states of a person or a group of people is reduced by repeated exposure of the stimuli which caused the emotional state
In this case the emotional conditions the volunteers experienced is that of being scared and shocked and the stimuli which caused it is the movie.Hence the movie was shown repeated number of times which reduced the emotional conditions of the volunteers.
34) In a psychology experiment, a group of volunteers are shown a violent short film that...