Let $$f(x)= [x]^{2}-[x+3]-3, x\in \mathbb R$$, where $$[\cdot]$$ is the greatest integer funtion. Then

A

f(x) > 0 only for $$x\in \left[4,\infty \right]$$

B

f(x) < 0 only for $$x\in \left[-1, 3 \right]$$

C

f(x) = 0 for finitely many values of x

D

$$\int_{0}^{2} f(x)dx=-6$$