1. $f(x) = \begin{cases} 3 & , \\ 5 & , \end{cases} \begin{matrix} x \neq 1 \\ x = 1 \end{matrix}$, $g(x) = x$, 則: (A) $\lim_{x \to 1} f(g(x)) = 5$ 且 $\lim_{x \to 1} g(f(x)) = 3$ (B) $\lim_{x \to 1} f(g(x)) = 3$ 且 $\lim_{x \to 1} g(f(x)) = 5$ (C) $\lim_{x \to 1} f(g(x)) = \lim_{x \to 1} g(f(x)) = 3$ (D) $\lim_{x \to 1} f(g(x)) = \lim_{x \to 1} g(f(x)) = 5$