Find the critical points and determine if the function is increasing or decreasing on the given intervals.
f(x) = 6x⁴ + 5x³

A) Critical points: x = 0, x = -5/6; Increasing on (-[infinity], -5/6) and (0, [infinity]) , decreasing on (-5/6, 0)
B) Critical points: x = 0, x = 5/6; Increasing on (-[infinity], 0) and (5/6, [infinity]) , decreasing on (0, 5/6)
C) Critical points: x = 0, x = -5/6; Increasing on (-[infinity], 0) and (-5/6, [infinity]) , decreasing on (0, -5/6)
D) Critical points: x = 0, x = 5/6; Increasing on (-[infinity], -5/6) and (5/6, [infinity]) , decreasing on (-5/6, 5/6)