\documentclass{webquiz}
\title{An easy example}
\begin{document}
  \begin{question}     % a quiz question
     Alice is twice as old as Betty.
     Betty is one year older than Claire.
     If Alice is $4$ how old is Claire?
     \begin{choice}[columns=2]    % multiple choice question
       \correct   $1$  % first choice - correct answer
       \feedback  If Claire is $1$ then Betty is $2$ and Alice is~$4$!

       \incorrect $2$  % second choice - incorrect
       \feedback  If Claire is $2$ then Betty is $3$ and Alice is~$6$.

       \incorrect $3$  % third choice  - incorrect
       \feedback  If Claire is $3$ then Betty is $4$ and Alice is~$8$.

       \incorrect $4$  % fourth choice - incorrect
       \feedback  If Claire is $4$ then Betty is $5$ and Alice is~$10$.
     \end{choice}
  \end{question}
\end{document}