Consider the monomial function f(x)=kxn, where k>0 and n is a positive even integer. Which one of the following properties does the graph of f necessarily have?
a) It is symmetric about the y-axis and possesses a single global maximum at the origin.
b) It is symmetric about the y-axis and possesses a single global minimum at the origin.
c) It is symmetric about the origin and possesses a single global minimum at the origin.
d) It is symmetric about the y-axis and possesses two equal global minima away from the origin.