If $f(x) = \begin{cases} 0, & x = 0 \\ x - 3, & x > 0 \end{cases}$,then $f(x)$ is:

• A
  An increasing function for $x \geq 0$.
• B
  $A$ strictly increasing function for $x > 0$.
• C
  $A$ strictly decreasing function at $x = 0$.
• D
  Not continuous at $x = 0$,therefore it is not an increasing function for $x > 0$.