Concept:Use the angle in a semicircle and the tangent–chord theorem to find the missing angle.Explanation:Since RS is a diameter, ∠RTS=90∘ (angle in a semicircle).The tangent UT meets chord TS, so by the alternate segment theorem, the angle in the alternate segment is also 25∘.Thus, the three relevant angles combine as:x+90∘+25∘=180∘x+115∘=180∘x=180∘−115∘x=65∘Answer:x=65∘, so option A is correct.
