Gerard conducts a study to examine the effectiveness of an exercise program on obese people. the participants must exercise for one hour every day for six months. by the end of the fourth month, gerard finds that 75 percent of the participants dropped out of the study. what kind of problem has gerard encountered in his study?

Attrition

Explanation:

Attrition: The term attrition refers to the process of a group getting smaller in number because members of the group are dropping out. Due to dropping out of the member of a group for different reasons in a research study, the reliability is being threatened.

In other words, if cases of a research study are getting lost over time then it will lead to attrition.

Key feature: Progressive loss of data in a research study or the wearing away.

The kind of problem Gerard has encountered in his study is attrition.

well i'm late but i think its: b, c, and e