Method 1

The total exterior angle of a polygon is 360^o

Each exterior angle of a duo-decagon (12- sided polygon) =$\frac{{{360}^{\circ }}}{12}={{30}^{\circ }}$

The interior angle = 180^o – 30^o = 150^o (sum of angles on a straight)

Method 2

The total angle in a regular polygon is given by (n – 2) 180^o

For a 12 sided polygon

The total angle will be (12 – 2)180^o =1800^o

Each interior angle will be $\frac{{{1800}^{\circ }}}{12}={{150}^{\circ }}$

Answer : Option C