Answer :

Pretty sure it is A. x4+10x2+48
Because:
If you multiply x^2 by X^2= x4
if you multiply 5^x by 2^x- 5*2=10 and x*x= x2 so it makes 10x2 
and then 8*6=46 
so if you put that all together then it is x4+10x2+48


(x² + 5x + 8)(x² + 2x + 6)
(x^4 + 2x³ + 6x² + 5x³ + 10x² + 30x + 8x² + 16x + 48)
(x^4 + 2x³ + 5x³ + 6x² + 10x² + 8x² + 30x + 16x + 48)
The answer to your problem is D. x^4 + 7x³ + 24x² + 48x + 48.