Which of the following is a first-order model relating E(y) to a. two quantitative independent variables, b. four quantitative independent variables, and c. five quantitative independent variables?

A. E(y)=0+1x1+2x2; E(y)=1x1+2x2+3x3+4x4; E(y)=0+1x1+2x2+3x3+4x4+5x5+6x25

B. E(y)=1x1+2x2; E(y)=0+1x1+2x2+3x3+4x4+; E(y)=1x1+2x2+3x3+4x4+5x5

C. E(y)=0+1x1+2x2; E(y)=0+1x1+2x2+3x3+4x4; E(y)=0+1x1+2x2+3x3+4x4+5x5

D. E(y)=0+1x1+2x2+3x21+4x22; E(y)=0+1x1+2x2+3x3+4x1x3; E(y)=0+1x1+2x2+3x3+4x4+5x5+