
factoring problems
I got these two wrong and am wondering what the correct answers are? I have bolded and italized my answers. Can you show me where I went wrong.
1. Which of the following polynomials can be factored as a difference of two squares?
A) 16x2 + 1
B) 9y2  1
C) x2 + 4x + 4
D) 144a2 + 16
E) all of the above
2. Factor 4x2  20x + 25. Select the answer.
A) 2x5
B) (2x5)2
C) (2x+5)2
D) 2x+5
E) none of these

For part 1 the questions says a difference of two squares.
so out of A, B, C and D which one has two squares being subtracted ?
for part 2, If you failed to factor the expression maybe you could try and expand C and B and see which one works.