[Tex/LaTex] How to label lists

Question

How do I implement what is shown below? If I just use "enumerate" each time, it doesn't get labeled (only the items get labeled).

Answer 1

Loading enumitem makes it easy to have a custom layout:

\documentclass{article}
\usepackage{amssymb}
\usepackage{enumitem}
\setlist[enumerate, 1]{label=(\arabic*), labelsep=1.35em}
\setlist[enumerate, 2]{label=\alph*., align=left, labelsep=1em}

 \begin{document}

 \begin{enumerate}
 \item \begin{enumerate}
 \item Mary dated $\Leftrightarrow$ John dated Mary
 \item Mary hibernated with John $\Leftrightarrow$ John hibernated with Mary
 \item Mary is John’s cousin $\Leftrightarrow$ John is Mary's cousin
 \end{enumerate}
 \end{enumerate}

 \end{document}