Which of the expressions below can be factored using the difference of squares method?

A. 100x2 - 55y2

B. 100x2 + 49y2

C. 100x2 - 49y2

D. 100x2 + 55y2

100x2 - 49y2 is the answer

The difference of the squares method is a short-cut method that is expressed a2 - b2 = (a + b) * (a-b). In this case, a2 and b2 should be perfect squares in which a and b are the square roots. In this case, 100 and 49 are perfect squares, hence the answer is C.