From a right cone of height h and with base radius r a cone has been cut of from the centre of the height. The volume of remaining frustum of the cone is.

• A. $$ {1 over3} {r^{2}}h$$
• B. $$ {1 over24} {r^{2}}h$$
• C. $$ {7 over24} {r^{2}}h$$
• D. $$ {1 over8} {r^{2}}h$$