Answer : Option A

Explanation :

Assume that the initial price of 1 Litre petrol = Rs.100 ,Benson spends Rs.100 for petrol,
such that Benson buys 1 litre of petrol

$MF#%\begin{align}
&\text{After the increase by 25%, price of 1 Litre petrol = }100 \times \dfrac{\left(100+25\right)}{100} = \text{Rs.}125\\\\\\
&\text{Since Benson spends additional 15% on petrol,}\\
&\text{amount spent by Benson = }100 \times \dfrac{\left(100+15\right)}{100} = \text{Rs.}115\\\\\\
&\text{Hence Quantity of petrol that he can purchase = }\dfrac{115}{125}\text{ Litre}\\
&\text{Quantity of petrol reduced = }\left(1 - \dfrac{115}{125}\right)\text{ Litre}\\\\
&\text{Percentage Quantity of reduction = }\dfrac{\left(1 - \dfrac{115}{125}\right)}{1} \times 100\\
&= \dfrac{10}{125}\times 100 = \dfrac{10}{5}\times 4 = 2\times 4 = 8\%
&\end{align} $MF#%