Answer :
we have the expression
24x^4+8x^2-32
Verify each option
N 1
(4x^2+4)(6x^2+8)
Applying distributive property
24x^4+32x^2+24x^2+32
24x^4+56x^2+32 ---------> is not the given expression
N 2
(4x^2+4)(-6x^2+8)
-24x^4+.... -----> is not the given expression
N 3
(4x^2-4)(6x^2+8)
24x^4+32x^2-24x^2-32
24x^4+8x^2-32 -----> is the given expression
therefore
The answer is