Clark needs to place increasingly larger amounts of money on his race track bets in order to experience the excitement he craves. when he tries to cut down on his betting habits, he feels restless and irritable. clark is most clearly experiencing symptoms of:

Clark is most clearly experiencing symptoms of a behavioral addiction.

Explanation:

A behavioral addiction refers to any main activity which has become the center and main focus of an individual's life.

Symptoms may include:

In this case, Clark needs to place larger bets to experience the same excitement and he feels restless and irritable if he cannot do so, he has a behavioral addiction to race tracks.

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.