Question:

Step 1: sin^2 A + sin^2 B + sin^2 C = 2 + 2 cos A cos B cos C. Given sum = 2 => cos A cos B cos C = 0 => one angle is 90°, so triangle is right-angled. Step 2: For a right triangle with C=90°, cos^2 A + cos^2 B + cos^2 C = 1. Step 3: sin A sin B sin C = sin A sin B = sin A cos A = (1/2) sin 2A, whose maximum is 1/2 (at A = 45°), so option C (≤ 1/4) is false. Step 4: Option D is undefined since tan 90° is undefined. Thus only A and B are true.