Explain why the function is discontinuous at the given number a$.($Select all that apply.$)$ f$($x$)=1$x $+3$ if x $31$ if x $=3$a $=3$ lim$$x$3$f$($x$)$ is not finite. f$(3)$ is defined and$$lim$$x$3$f$($x$)$ is finite, but they are not equal. lim$$x$3+$f$($x$)$ and$$lim$$x$3$f$($x$)$ are finite, but are not equal. f$(3)$ is undefined. none of the above Sketch the graph of the function.