How to give an evidence in support of the arenium ion mechanism?


> 
> Outline the mechanistic steps involved in the arenium ion mechanism for
>  aromatic electrophilic substitution. Draw the energy profile diagram for the proposed mechanism. Give one evidence in support of the proposed mechanism.
> 
> 
> 


I can solve the first two questions but I got confused about what the last question exactly asking for. Any help will be appreciated.




You say you've already drawn the energy profile diagram for your proposed mechanism , now you want to make sure that your reaction mechanism proceeds through the most stable transition state , ( Least activation energy ) and therefore , on the energy profile diagram , the peak occuring at the transition state should not be too high .Also you wanna make sure that your final products have energies lesser than the reactants , because in that case , your $\Delta H$ would be $-ve$ and from the equation $\Delta G=\Delta H-T\Delta S $, there would be a greater chance your reaction moves forward.[![enter image description here](https://i.stack.imgur.com/dXZEJ.png)](https://i.stack.imgur.com/dXZEJ.png)


You also should have a look at [this](https://www.khanacademy.org/science/organic-chemistry/aromaticcompounds/reactions-benzene/v/electrophilic-aromatic-substitution)


 0