Task: Question Answering
Input (English): Question: If a, b and c are the sides of a triangle, and a2 + b2 + c2 = bc + ca + ab, then the triangle is

 Option A: equilateral

 Option B: isosceles

 Option C: right-angled

 Option D: obtuse-angled

 Option E: None of these
Output (English): Option A