James conducts a survey to study the relationship between cell phone use and grades earned during the fall semester. James suspects that there might be a lot of other factors that affect grades besides cell phones. Which of the following could be a confounding variable in James's study?
a. Grade earned during the spring semester
b. Time spent studying
c. Grade earned during the fall semester
d. Time spent using a cell phone

b. Time spent studying

Step-by-step explanation:

From the answer, choices provided it can be said that the confounding variable in James' study would be the Time spent studying because it is directly affecting the other variables in the study. The more time spent studying means the less time that the individual has spent using a cell phone, while at the same time drastically increasing the likelihood of getting better grades. Therefore, directly changing the values of both of these variables.