Kavan saved \[\frac{6}{7}\] of his salary every month for 4 months. His monthly salary was Rs. 2100 for the first 2 months. In the third month, he had an increment of Rs. 700. How much money did he save altogether during the 4 months?

• A.  Rs. 3600              
• B.         Rs. 4800              
• C.                         Rs. 8400              
• D.         Rs. 2800