B?
(1) The first 4 four terms of S are (1 + 1)² , (2 + 1)² , (3 + 1)² , and (4 + 1)².
INSUFFICIENT. You only know the first four terms. Unless there's a formula such as f(n)=n+2 (made up randomly) that applies to all numbers, you cannot assume that terms after the first 4 follow what apparently seems like nth term = (n+1)^2.
(2) For every x, the xth term of S is (x + 1)².
SUFFICIENT. It's worded weirdly but I think "for every x" means "for any number (integer probably) x that refers to the term in S."
Hmmm...