Tables for functions $f$ and $g$ are given. Evaluate each expression, if possible.
(a) $(g \circ f)(1)$
(b) $(f \circ g)(4)$
(c) $(f \circ f)(3)$
$$\begin{array}{c|cc|c}\boldsymbol{x} & \boldsymbol{f}(\boldsymbol{x}) & \boldsymbol{x} & \boldsymbol{g}(\boldsymbol{x}) \\\hline 1 & 4 & 1 & 2 \\\hline 2 & 3 & 2 & 3 \\\hline 3 & 1 & 3 & 4 \\\hline 4 & 2 & 4 & 5
\end{array}$$