\documentclass[pst2pdf]{webquiz}
\usepackage{pst-all,pst-3dplot}
\title{A pst2pdf example}
\begin{document}
  \begin{question}     % a quiz question
      Which of the equations below could describe the following surface?

        \begin{pspicture*}(-4,-4)(4,4)
          \psplotThreeD[linecolor=blue, plotstyle=curve, drawStyle=yLines,
                      yPlotpoints=30, xPlotpoints=30, linewidth=1pt](-4,1)(-4,1){
                        x dup mul y dup mul add 1.01 exp}
          \pstThreeDCoor[linewidth=1pt, xMin=-4,xMax=4,yMin=-4,yMax=4,zMin=-2,zMax=6]
        \end{pspicture*}

      \begin{choice}
        \incorrect \( z=\log(x^2+y^2) \)
        \correct   \( z=e^{x^2+y^2} \)
        \incorrect \( z=1-e^{x^2+y^2} \)
        \incorrect \( z=\dfrac1{x^2+y^2}\)
      \end{choice}
  \end{question}
\end{document}
