I need assistance with formulating my proposal statement, im unsure of the most important variable and why

"The dependent variable _______ is determined by independent variables ________, _________, ________, and ________." Identify and defend the "primary" independent variable, or the variable believed to have the strongest impact on the dependent variable: "The most important independent variable in this relationship is ________ because _________."

2) Definition of Variables For each variable defend why each determines the dependent variable.

Data: