The correct option is A x2+4x−14
Let the expression that should be added be y.
Hence,
(x2−3x+8)+y=(2x2+x−6)
On rearranging the terms, we get
y=(2x2+x−6)−(x2−3x+8)
2x2 + x − 6 x2 − 3x + 8(−) (+) (−) x2 + 4x − 14
y=x2+4x−14
So, x2+4x−14 should be added to x2−3x+8 to get 2x2+x−6.