11. A liquid is flowing in a tube which has a single constriction, as sketched below. Vertical tubes open to the atmosphere are connected at points X and Y, so that the fluid rises to the levels indicated. What will happen to the levels when the stopcock is closed? a) the levels will become equal at the level originally present in tube Y b) both levels will rise reaching a common level c) the levels will become equal at a level intermediate between those of X and Y d) the levels will not change e) the level in each tube will rise but the difference in levels will not change Y STOPCOCK X