The answer is the independent variable
Here, we want to select the choice that can impact the dependent variable
A dependent variable is one which has its value depending on an input
This input is called the independent variable
In clear terms, we are sourcing the values of the dependent varaible from the independent
In a well designed experiment, the control, constant and the extraneous variable will not affect the dependent variable. Only the independent variable has an effect or impact on the activities, values or actions of the dependent variable