(D) 125°
Since OT ⊥ PT (radius ⊥ tangent), ∠OTP = 90°. In △OTP, ∠TOP = 180° − 90° − 35° = 55°. So ∠x = 180° − 55° = 125° (linear pair / reflex consideration: x = 90° + 35° = 125°).
Key facts: (1) Tangent ⊥ radius at point of contact, so ∠OTP = 90°. (2) Angle sum in △OTP gives ∠POT = 55°. (3) Angle x (the obtuse/reflex angle at O on the other side) = 180° − 55° = 125°. Examiners expect you to use Theorem 10.1 and the angle-sum property of a triangle.