(A) \( f(x)=x-[x] \) where \( [x] \) denotes the largest integer less than or equal to the real number \( x \) .

(B) \( f(x)=\sin \frac{1}{x} \) for \( x \neq 0, f(0)=0 \)

(C) \( f(x)=x \cos x \)

(D) \( f(x)=x \cos \frac{1}{x} \)