Let f be a polynomial function such that for all real x f (x² + 1) = x4 + 5x² + 2, then ∫ f (x) dx is
(A) x³/3 +3x²/2 - 2x + C
(B) x³/3 +3x²/2 + 2x + C
(C) x³/3 +3x²/2 - 2x + C
(D) x³/3 +3x²/2 + 2x + C