Answer:
- Explanatory
Step-by-step explanation:
Explanatory variable is elucidated as the variable that could affect the response variable. This variable is quite identical with the independent variable as it can be controlled or changed that may affect the response variable(which is similar to dependent variable). However, the observational studies observe the natural responses without any manipulation and therefore, these variables cannot be changed always. In the given example, the 'number of hours spent on studying for the test' would be the explanatory variable as it directly influences the response variable i.e. 'grades.'