What indicate $X,Y$ in the given diagram?

The given diagram represents the symplastic pathway of water movement. In symplast pathway, water travels from one cell to next through plasmodesmata. The symplast consists of an entire network of cell cytoplasm which is interconnected by plasmodesmata. Hence, in the diagram, X is the cell surface membrane and Y is plasmodesmata or plasmodesma.

So, the correct answer is A.