math help!?

Question

find the mistake kindov problem.

(x+1)(x-1)-(x+1)(x+2) -3
---------------------------- = -----
(x+1)(x-7) x-7

i know the answer wasnt a so i didnt post that one. if it also wouldnt be a problem could you explain why thats the right answer.

B After the polynomials are multiplied, they must be simplified, so the answer should be -1
---
x-7

C The polynomials should be multiplied, so the answer should be
(x^2-1)-(x^2+3x+2)
-------------------------
x^2-6x-7

D (x - 1) and (x + 2) cannot be combined after canceling the (x + 1) terms, so the answer should be
(x-1)-(x+2)
-------------
x-7

E The expression cannot be simplified.
F This solution is correct.

Answer 1

(x+1)(x-1)-(x+1)(x+2)
----------------------------
(x+1)(x-7)

= {(x+1)[(x-1) -(x+2]}/[(x+1)(x-7)]
= [(x-1)-(x+2)]/(x-7)
= (x-1-x-2)/(x-7)
= -3/(x-7) <-- correct answer

This is the same as answer D but they did not simplify it.