The correct option is C Assertion is correct but reason is incorrect.
Osmotic pressure will result in osmotic inflow of water into the cell. The osmotic inflow of water into the cell will result in swelling of protoplasm, which will generate turgor. The increased turgor will cause pressing of protoplasm against the cell wall with pressure, called as turgor pressure. The turgor pressure causes cell protoplasm to press tightly against the cell wall. It does not results in increase in cell number. Cell number will increase by cell division through mitosis.