By seelling an article for ₹720, a shopkeeper gains 20%. If he sells it for ₹210, what is his gain or loss percentage ?

A

Loss, $$6\frac{2}{3}$$%

B

Gain, $$7\frac{1}{7}$$%

C

Gain, $$6\frac{2}{3}$$%

D

Loss, $$7\frac{1}{7}$$%