Dr. Martinez is studying the effects of diet on mental alertness. Each morning for two weeks, participants in Dr. Martinez's study eat a breakfast that is either high in carbohydrates or high in protein. Dr. Martinez then measures the participants' abilities to solve geometry problems. What is the dependent variable in this study?

The correct answer is: The participants' abilities to solve geometry problems.

Explanation:

Researches contain both dependent and independent variables.

In a research the dependent variable is the variable that the researcher wants to identify if it changes by modifying the independent variables.

Independent variables are multiple factors that if modified they may or may not change the dependent variable.

In this particular case, Dr Martinez wants to prove the effects of diet on mental alertness. He proceeds to instruct the participants to eat breakfast that's either high in carbohydrates or high in protein (Independent variables) and then Dr. Martinez then measures the participants abilities to solve geometry problems (Dependent variable).

In conclusion, the dependent variable in this study is: Participants' abilities to solve geometry problems.