Explanation

(c)
Carbon and hydrogen are estimated in organic compounds by Liebig's method
$C + 2CuO\overset{\mathrm{\Delta}}{\rightarrow}2Cu + CO_{2}$
$2H + CuO\overset{\mathrm{\Delta}}{\rightarrow}Cu + H_{2}O$
Percentage of carbon and hydrogen is calculated from the weight of $CO_{2}$ and $H_{2}$ produced