Answer : Option B

Explanation :

Let the speed of Arun = x kmph
and the speed of Anil = y kmph
distance = 30 km

$MF#%\begin{align}
&\text{We know that }\dfrac{\text{distance}}{\text{speed}} = \text{time}\\\\\\\\
&\text{Hence}\\\\
&\dfrac{30}{x} - \dfrac{30}{y} = 2\text{...........(Equation1)}\\\\
&\dfrac{30}{y}- \dfrac{30}{2x} = 1\text{...........(Equation2)}\\\\
&\text{Equation1 + Equation2} \Rightarrow \dfrac{30}{x} - \dfrac{30}{2x} = 3\\\\
&\Rightarrow \dfrac{30}{2x} = 3\\\\
&\Rightarrow \dfrac{15}{x} = 3\\\\
&\Rightarrow \dfrac{5}{x} = 1\\\\
&\Rightarrow x = 5\\\\
&\text{Hence Arun's speed = 5 kmph}\end{align} $MF#%