Refer to the function f shown in the figure. Use the graph to estimate the indicated function values and limits.
(A) $\lim _{x \rightarrow 1^{-}} f(x)$
(B) $\lim _{x \rightarrow 1^{+}} f(x)$
(C) $\lim _{x \rightarrow 1} f(x)$
(D) $f(1)$
(E) Is $f$ continuous at $x=1 ?$ Explain.