An elections officer wants to model voter turnout y in a pre

An elections officer wants to model voter turnout (y) in a precinct as a function of type of election, national or state.
Write a model for mean voter turnout, E(y), as a function of type of election.

A) E(y) = Bo+B1x1 +B2x2, where x1= 1 if national, 0 if not and x2= 1 if state, 0 if not

B) E(y) = Bo+ B1x, where x = 1 if national, 0 if state

C) E(y) = B0+ B1x + B2x2 , where x = voter turnout

D) E(y) = B0+ B1x, where x = voter turnout

Solution

(A) looks to be the correct answer. E(y) = Bo+B1x1 +B2x2, where x1= 1 if national, 0 if not and x2= 1 if state, 0 if not

Take solution B. It is incorrect because the moment you substitute x for state i.e. 0, E(y) = B_0 It does not talk about variability in state elections.

Solutions C and D are automatically ruled out since they are not a function of state/national.