Osmosis is helpful to plant because

Osmosis is the process of movement of solvent molecules from the region of higher concentration to the lower concentration. The cells absorb water by the process of osmosis from its surrounding. On absorption of water the turgor pressure inside the cells increases. It helps to maintain the shape of the cell. It helps in the growth, development, mechanical support and prevents wilting.

The water pressure inside plant cells is called turgor pressure, and it is maintained by a process called osmosis. It also regulates the turgor movement by creating pressure gradients. Example, opening and closing of stomata, drooping of leaves by touch -me -not plant etc

So, the correct answer is option C.