Choose the best reason why the function $$f(x)=\left\lbrace \begin{array}{ll} \frac{x^2-49}{x+7} &\quad {\rm if}\quad x\not=-7, \\ 7 & \quad {\rm if} \quad x=-7 \end{array}\right.$$ is discontinuous at $a=-7$.

A. $\displaystyle\lim_{x\to a} f(x)\not = f(a)$.

B. $\displaystyle\lim_{x\to a} f(x)$ doesn't exist.

C. The function is not defined at the point given.

Answer: ? A B C .