Question

Suppose that the domain of the function, f, is all real numbers and its derivative is given by
f'(x)= ((x-1)(x-4)^2)/ 1+x^2.

Which of the following is true about the function f?

I. f is decreasing on (-infinity, 1)
II. f has a relative minimum at x=4
III. f is concave up at x=8

a: I only
b:I and II only
c: I and III only
d: II and III only
e: I, II, and III