Hi,
I would rather that this is a geometry question (no trigonometry required).
Statement 1: To be able to visualize, drag the line WY such that the base Y coincides with Z. Now, one knows that if a>b; then, WY has to be longer than XZ. Is statement 1 sufficient? Yes
Statement 2: If a + b > 270; it does not give any clue as to whether a is greater than b or if a is lesser than b. For example, if a+b = 272; then, a could be 135 and b could be 137 (XZ is longer). Or a could be 137 and b could be 135 (WY is longer). Because of these contradictions, is statement 2 sufficient to answer the question? No
Hence, A
Hope this helps. Thanks.
Naveenan Ramachandran
4GMAT, Dadar(W) & Ghatkopar(W), Mumbai