Answer:
B
Step-by-step explanation:
If C is the correct answer and if the final result is multiplied out, where does the minus sign in a^4 - b^4 come from? All pluses don't make a minus. A is incorrect.
If D is correct, then a^2 - b^2 should be further factored producing a different kind of answer, like (a + b)^2(c-d)^2 which is not the same as a^4 - b^4. So D is not correct.
The first step in factoring a^4 - b^4 is (a^2 + b^2)(a^2 - b^2) A doesn't lead you anywhere. A is incorrect. The answer must be B.
a^4 - b^4 = (a^2 - b^2)(a^2 + b^2) The first term factors.
a4 - b^4 = (a + b)(a - b) (a^2 +b^2)
