ACT Problem 36

$$\begin{array}{lcl} 36.\;The\;volume\;of\;a\; right\; cylinder\;is\;\pi, \\ which\;of\;the\;following\;must\;be\;true?\\ \\ I.\;h=\frac{1}{r^{2}}\\ II.\;h=r\\ III.\;r\cdot h=1\\ \\ (F)\; I\;only\\ (G)\; II\;only\\ (H)\; II\;and\;III\;only\\ (J)\; I\;and\;III\;only\\ (K)\; I,\;II\;and\;III\\ \end{array}$$