The pie chart shows the distribution of grades obtained by a group of students in a test. The number of students who scored grade C is twice the number who scored grade B, and \[\frac{3}{5}\] of the students scored grades B and C. Find the angle of the sector which represents grade C.

• A.  \[{{108}^{o}}\]                                
• B.                         \[{{144}^{o}}\]
• C.                         \[{{216}^{o}}\]                                
• D.                         \[{{288}^{o}}\]