Differentiate the function below:
y=(x² +4) (x² -5) ⁹
a) y' = 2x(x² - 5) ⁹ + 18x(x² + 4) (x² - 5) ⁸
b) y' = 2x(x² - 5) ⁸ + 9(x² + 4) (x² - 5) ⁸
c) y' = 2x(x² + 4) (x² - 5) ⁸ + 9(x² + 4) (x² - 5) ⁸
d) y' = 2x(x² - 5) ⁹ - 9(x² + 4) (x² - 5) ⁸