\documentclass[12pt]{article}
\usepackage{ntnu}
\usepackage{ntnu-math}

\author{TODO: STUDENTNUMMER}
\title{Exam v2021}

\usetikzlibrary{automata, positioning, arrows.meta}

\newcommand{\I}{Option 1 is correct}
\newcommand{\II}{Option 2 is correct}
\newcommand{\III}{Option 3 is correct}

\renewcommand{\theenumi}{\arabic{enumi}}
\renewcommand{\theenumii}{(\arabic{enumii})}
\renewcommand{\theenumiii}{\alph{enumiii})}

\begin{document}

  \ntnuTitle{}
  \break{}

  \tableofcontents

  \begin{excs}
    \exc{}
    \begin{subexcs}
      \subexc{}

    \end{subexcs}
  \end{excs}

\end{document}
