The correct option is C 12
Given the measure of each interior angle of a regular polygon is five times the measure of its exterior angle.
Each interior angle of a regular polygon = 180o(n−2)n where n = number of sides of polygon
Each exterior angle of a regular polygon = 360on
According to question,
180o(n−2)n=5×360on
=>n−2=10
=>n=12
Number of sides of the polygon =12