A real-valued univariate function f=f(x) has a jump discontinuity at a point [tex]x_0[/tex] in its domain provided that
[tex]\lim \limits_{x\to x_0^-}f(x)=A_1[/tex]
and
[tex]\lim \limits_{x\to x_0^+}f(x)=A_2[/tex]
both exist and that [tex]A_1\neq A_2.[/tex]
As you can see at x=-3,
[tex]\lim \limits_{x\to -3^-}f(x)=6,[/tex] [tex]\lim \limits_{x\to -3^+}f(x)=9[/tex] and [tex]6\neq 9.[/tex]
Therefore, there is a jump discontinuity at x=-3.
Answer: correct choice is A.
