【名词&注释】
充分条件(sufficient condition)、充分必要条件(necessary and sufficient condition)、非必要、非齐次线性方程组(nonhomogeneous linear equation set)
[单选题]非齐次线性方程组(nonhomogeneous linear equation set)有解时,a应取下列何值()?
A. -2 B. -4 C. -6 D. -8