CMOS Circuit Question
You simply need to break it down moving from the output to the input.

C = 1: Out = floating (i.e. X) unless the node on the inverter is driven low.

C= 0: Out = 0 unless the PMOS on the inverter has strength enough to drive the NMOS (with /C on it), but since this is driven through another NMOS (with C on it) it's hard to tell.

This question as posed needs transistor sizing information to be of any value at all.