\documentclass[theme=vibrant]{webquiz}
\title{A multiple choice example with zero or more correct answers}
\renewcommand\thechoice{\roman{choice})}
\begin{document}
  \begin{question}     % a quiz question
     Which of the following integers are prime?
     % multiple (0 or more) correct answers rendered in three columns
     \begin{choice}[multiple, columns=3]
       \correct   $17$ \feedback Yes, the only divisors of $17$ are $1$
                  and $17$
       \incorrect $12$ \feedback No, $12 = 3\times 4$
       \incorrect $27$ \feedback No, $27=3^3$
       \incorrect $91$ \feedback No, $91 = 3\times 17$
       \incorrect $1$ \feedback One is not a prime number because it
                  is invertible
       \correct   $97$ \feedback Yes, the only divisors of $97$ are $1$
                  and $97$
     \end{choice}
  \end{question}
\end{document}
