For the Regression Equation $= 20 + 8 x _ { 1 } + 5 x _ { 2 } + 3 x _ { 1 } x _ { 2 }$

Multiple Choice

For the regression equation $= 20 + 8 x _ { 1 } + 5 x _ { 2 } + 3 x _ { 1 } x _ { 2 }$ , which combination of $x _ { 1 }$ and $x _ { 2 }$ , respectively, results in the largest average value of y?

A) 3 and 5.
B) 5 and 3.
C) 6 and 3.
D) 3 and 6.