Dr. Peters investigated the relationship between academic performance of middle school students and the length of recess in the school. The study revealed that the longer the periods of recess for students, the better were their performances. This study is indicative of a:.

Positive correlation

Explanation:

Dr. Peters investigation in respect of the relationship between academic performance of middle school students and the length of recess in the school. The study which revealed that the longer the periods of recess for students, the better were their performances is a study which indicates positive correlation.

Positive correlation simply means a relationship between two variables,this two variables always move towards the same direction.for example: if one variable increases the other variable will also increase and vice versa.

i am pretty sure it is d.