# Carbogen is _____________

$\begin{array}{1 1}(a)\;Pure\;form\;of\;carbon\\(b)\;COCl_2\\(c)\;Mixture\;of CO\;and\;CO_2\\(d)\;Mixture\;of\;O_2\;and\;CO_2\end{array}$

90% $O_2$+10% $CO_2$
Hence (d) is the correct answer.