A) Do municipalities with fewer per capita single-parent households have lower unemployment rates?

B) Is there a difference in student knowledge obtained viaonlineversus traditional courses?

C) Does a high frequency of social media exposure increase the likelihood of depression?

Please help to figure out what are the UoA (unit of analyses), Independent Variable, Dependent Variable, and EV for each A, B, and C above?

Also, how to define the IV, DV, and EV for each A,B, and C?