(A) n=w by the corresponding angles theorem.
(B) This is the correct answer. n=s by the vertical angles theorem and s and x are supplementary by the same-side interior angles theorem. Thus, n and x are supplementary, and are not always equal.
(C) n=z by the alternate exterior angles theorem.
(D) s=w, so (s+w)/2 = (s+s)/2 = s. Since n=s by the vertical angles theorem, n=s.
(E) n and w are equal by the corresponding angles theorem, and w and y are supplementary as they form a linear pair. Thus, n+y=180, and it follows n=180-y.