As explained D is Dividend option and G is growth option. However, under Dividend option normally there will be two options - 1. Dividend payout and 2. Dividend re-investment. In payout, the dividend declared witll be paid to the investor. In re-investment, on the date of declaring the dividend, at the NAV of that day, the dividend will be re-invested in the same scheme and additional unit will be alloted and added back to the holdings of the investor.