For a real number x let [x] denote the largest number less than or equal to x. For ` x in R` let f (x)=[x] `sin pix`. Then
A. If is differentiable on R.
B. f is symmetric about the line x=0
C. `int_(-3)^(3)f(x)dx=0`
D. For each real `alpha`, the equation `f(x) -alpha =0` has infinitely many roots.