The correct option is (a) 9
Easiest explanation: A hexagon has 6 sides. We obtain the diagonals by joining the vertices in pairs.
Total number of sides and diagonals = ^6C2 = \(\frac{6 * 5}{2 * 1}\) = 5×3 = 15. This includes its 6 sides also. So, Diagonals = 15 – 6 = 9. Hence, the number of diagonals is 9.