Cis and Trans Isomerism given three different groups around the reference plane
Am I on the right track?


Generally, yes. For this question, yes but you have over thought this question.

For starters, any answer with Y can be totally eliminated as Y is neither cis nor trans. Now you are down to answers 'A.' and 'D.'

Here you correctly determined the E and Z configurations of molecules with identical functional groups, but could have saved yourself some effort if you had recognized W and Z are identical molecules that are inversions/180° rotations of each other. Thus it can't be D. and the answer is in fact:


  A.