12
15
10
14
Correct answer is D
each interior angle of a polygon = (n−2)×180n where n = no of side of a polygon
each exterior angle of a polygon = 360n
then (n−2)×180n = 6× 360n
= (n - 2) 180 = 2160
= 180n - 360 = 2160
= 180n = 2160 + 360
= 180n = 2520
therefore, n = 2520180 = 14.