The correct option is D -2
3x2+1(x2+1)3=(Ax+B)(x2+1)2+(Cx+D)(x2+1)+Ex+F(x2+1)3
3x2+1=(Ax+B)(x2+1)2+(Cx+D)(x2+1)+(Ex+F)−−(1)
comparing the co-efficient of x5,x3,x
we get A=0,C=0;E=0
3x2+1=B(x2+1)2+D(x2+1)+F
comparing x4 co-efficient B=0 and x2
we get , D=3;
So, 3x2+1=3(x2+1)+F
⇒F=−2