[假設語氣]一定要"假設"嗎?

If you ________ thinking we'd profitable again soon, you'd be disappointed.

(a)were
(b)was
(c)are
(d)had been

書上的參考答案是(a),雖然我的因為認為題目是在考假設語氣,所以were會是我的備選答案,但是(c)真的不行嗎?