Bill wants to write down the equation which describes the model for determining quarter-life crisis. He is using optimism, locus of control, income, and years since completing college as explanatory variables. Which of the following equations is most appropriate?
A. = a + b1X1 + b2X2 + 3X3 + 4X4
B. Y = 0 + 1Xi
C. Yi = 0 + 1X1 + 2X2 + 3X3 + 4X4 + ei
D. = a + bXi
E. None of the above