\documentclass{jarticle}
\usepackage{array}
\usepackage{tabularx}
\usepackage{enumerate}

\newcounter{row}
\renewcommand\therow{\alph{row}}
\newenvironment{rowenum}
  {\setcounter{row}{0}%
    \par\noindent\tabularx{\linewidth}[t]
    {*{3}{>{\stepcounter{row}\makebox[1.8em][l]{(\therow)\hfill}}X}}%
  }
  {\endtabularx}

\newcounter{gyou}
\renewcommand\thegyou{\arabic{gyou}}
\newenvironment{gyouenum}
  {\setcounter{gyou}{0}%
    \par\noindent\tabularx{\linewidth}[t]
    {*{3}{>{\stepcounter{gyou}\makebox[1.8em][l]{(\thegyou)\hfill}}X}}%
  }
  {\endtabularx}

\newcounter{gyo}
\renewcommand\thegyo{\arabic{gyo}}
\newenvironment{gyoenum}
  {\setcounter{gyo}{0}%
    \par\noindent\tabularx{\linewidth}[t]
    {*{2}{>{\stepcounter{gyo}\makebox[1.8em][l]{(\thegyo)\hfill}}X}}%
  }
  {\endtabularx}

\begin{document}

\begin{enumerate}[\bfseries{問題} 1]
\item 選択せよ。
\begin{gyoenum}
part 1 & part 2 \\
part 3 & part 4 \\
\end{gyoenum}

\item 洗濯せよ。
\begin{gyouenum}
part 1 & part 2 & part 3 \\
part 4 & part 5 & part 6 \\
\end{gyouenum}
\end{enumerate}

\begin{enumerate}
\item 選択せよ。
\begin{rowenum}
part 1 & part 2 & part 3 \\
part 4 & part 5 & part 6 \\
\end{rowenum}
\item 選択せよ。
\begin{rowenum}
part 1 & part 2 & part 3 \\
part 4 & part 5 & part 6 \\
\end{rowenum}
\end{enumerate}

\end{document}
