Achievement motivation is usually defined as a. the need to reach a level of self-perfection b. the fulfillment of culturally dictated goals c. meeting the needs of those we seek to d. a desire to excel or outperform others

d. a desire to excel or outperform others

Explanation:

Simply put, motivation is the movement for action. These are the reasons that lead an individual to perform a certain action. There are three types of motivation, which are called fulfillment for power, achievement and affiliation.

The achievement motivation represents the desire to perfect oneself and to do the activity as best as possible. That is, this kind of motivation can be interpreted as the desire to overcome oneself or to overcome others.

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.        

the answer would be in this answer. someone already asked the question.