# Water gas has

$\begin{array}{1 1}(a)\;40-50\%CO,45-50\%H_2\\(b)\;70-80\%,20-25\%H_2\\(c)\;5-15\%CO,45-50\%H_2\\(d)\;90-95\%CO,5\%H_2\end{array}$

Water gas has $40-50\%CO,45-50\%H_2$
Hence (a) is the correct answer.