Augmenting the Regression Equation Derived from the Production Function, G_Y

Augmenting the regression equation derived from the production function, g_Y = a
+ b₁ g_K + b₂ g_L, by adding other possible explanatory variables in order to create the regression equation g_Y = a + b₁ g_K + b₂ g_L + b₃Z₁ + ... + b_n+2Z_n, the coefficients of the Z variables tell us the effect of the Z variables on:

A) the growth of the factors of production.
B) the levels of the Z variables.
C) the level of technology.
D) the rate of total factor productivity growth.