assume a resourceful fan has discovered a function f defined over the infinite extent of concievable and inconcievable time that matches the difference in electric potental between the two cheeks during the extent of their initial quest to become a pokemon master, which he calculated by evaluating the intensity of the light of this thunder shocks.

we can say that f(|x|) is:

a) even

b) non-negative

c) periodic

d) none of the above