Given the function π f(x)=x³-6x²+5 π, find the intervals in which the function increases or decreases.
a) Increases: (-[infinity], 1); Decreases: (1, [infinity])
b) Increases: (1, [infinity]); Decreases: (-[infinity], 1)
c) Increases: (-[infinity], 5); Decreases: (5, [infinity])
d) Increases: (5, [infinity]); Decreases: (-[infinity], 5)