Suppose O1 is center of small circle and O2 of bigger one. Now O1 A is perpendicular at A on AC and O2C is perpendicular at C on the tangent AC. If I join O1 O2 then angle O1AC = angle O1AB + angle BAC = 90. Similarly, angle O2CA = angle O2CB + angle BCA.
This means angle B = angle A + angle C so B is 90.
Answer B is right angled.