Explanation

(c)
An aromatic hydrocarbon (empirical formula $C_{5}H_{4}$)
$+ H_{2}SO_{4} \rightarrow$ monosulphonic acid
$\because$ 0.104 g of monosulphonic acid required 10 mL
of $\frac{N}{20}$ NaOH for complete neutralisation
$\therefore\ \ \ \frac{0.104}{n(5 \times 12 + 4 \times 1)} = \frac{1}{20} \times 10 \times 10^{- 3}$
$n = \frac{104}{32} = 3.25 \approx 3$
The molecular formula of hydrocarbon will be $C_{15}H_{12}$.