Only (A) and (D) are feasible, and (A) gives the larger $Z=100$

According to Beale's method, the solution to the quadratic programming problem: Max $Z=10x_1+25x_2-10x_1^2-x_2^2-4x_1x_2$ subject to $x_1+2x_2+x_3=10$, $x_1+x_2+x_4=9$, $x_1,\dots,x_4\ge0$ is: