Integrate the following expression: ∫ x³/√1+x²)dx. Which of the following options correctly represents the antiderivative of the given expression? A) ∫ x²/√1+x²)dx, B) ∫ x⁴)/√1+x²)dx, C) ∫ x³/√1+x²)dx, D) ∫ x³/√1+x²)dx.