JEE Math Practice Question

If $$a>0$$ and discriminant of $$\,a{x^2} + 2bx + c$$ is $$-ve$$, then $$\left| {\begin{matrix} a & b & {ax + b} \\ b & c & {bx + c} \\ {ax + b} & {bx + c} & 0 \\ \end{matrix} } \right|$$ is equal to

1. A.$$+ve$$
2. B.$$\left( {ac - {b^2}} \right)\left( {a{x^2} + 2bx + c} \right)$$
3. C.$$-ve$$
4. D.$$0$$