1 $\begin{matrix}
OH\,\,\,\, \\
|\,\,\,\,\,\,\,\, \\
C{{H}_{3}}-CH-C{{O}_{2}}H \\
\end{matrix}$
2
3 $\begin{matrix}
C{{H}_{3}}-CH-C{{H}_{2}}-C{{O}_{2}}H \\
|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
OH\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
\end{matrix}$
4 All of these