Correct Answer - B
(i) Sum of the angles of a triangle is `180^(@)`. Vertically opposite angles are equal.
(ii) Use the relation `/_APB =(1)/(2) /_ AOB =x`.
(iii) `/_OCA = /_ PCB . ` ( as they are vertically opposite angles )
(iv) Sum of the angles of a triagnel is `180^(@)`.