An Elections Officer Wants to Model Voter Turnout $( y )$

An elections officer wants to model voter turnout $( y )$ in a precinct as a function of the type of precinct.
Consider the model relating mean voter turnout, $E ( y )$ , to precinct type:
$$\begin{array} { l l } E ( y ) = \beta _ { 0 } + \beta _ { 1 } x _ { 1 } + \beta _ { 2 } x _ { 2 } , \text { where } & x _ { 1 } = 1 \text { if urban, } 0 \text { if not } \\& x _ { 2 } = 1 \text { if suburban, } 0 \text { if not } \\& \text { (Base level = rural) }\end{array}$$
Interpret the value of $\beta _ { 0 }$ .

A) the mean voter turnout for urban precincts
B) the mean voter turnout for rural precincts
C) the difference between the mean voter turnout for urban and rural precincts
D) the y-intercept of the line