Integrate the following expression: (-6x²)/(sqrt(4x-x²))dx. Which of the following options represents the correct integral?

a) ∫(-6x²)/(sqrt(4x-x²))dx
b) ∫(-6x²)/(2√(4-x))dx
c) ∫(-6x²)/(2√(4+x))dx
d) ∫(-6x²)/(2√(x-4))dx