Maximize the Object Function $z = 2 x + y$ Subject to the Constraints

Maximize the object function $z = 2 x + y$ subject to the constraints $3 x + y \leq 15,4 x + 3 y \leq 30 , x \geq 0 , \text { and } y \geq 0$ .

A) The maximum value is 10 at $( 2,6 )$ .
B) The maximum value is 4 at $( 1,2 )$ .
C) The maximum value is 10 at $( 3,4 )$ .
D) The maximum value is 12 at $( 3,6 )$ .
E) The maximum value is 5 at $( 2,1 )$ .