Answer:
Option C.
Explanation:
A triangle ABC is rotated counterclockwise (about a point P) by an angle = 100° to create a new triangle A'B'C'.
After rotation points A,B and C will overlap A', B' and C' respectively but angles A, B and C of triangle ABC will remain unchanged.
Therefore, ∠C'A'B' ≅ ∠CAB ≅ 70°
Option C will be the answer.