Nitration of aniline in strong acidic medium also gives $\mathrm{m}$-nitroaniline because 

In the reaction 

the electrophile involved is    [NEET (UG) 2018]

The product of the given reaction  

The product $\text{'}\mathrm{B}\text{'}$ is : 

The nucleophilicity order of the given nucleophiles :-    

($\mathrm{i}$) ${\mathrm{C}}_2{\mathrm{H}}_5\stackrel{⊝}{\mathrm{O}}$

($\mathrm{ii}$) ${\mathrm{C}}_6{\mathrm{H}}_5\stackrel{⊝}{\mathrm{O}}$

($\mathrm{iii}$) $\stackrel{⊝}{\mathrm{O}}\mathrm{H}$

($\mathrm{iv}$) $\stackrel{\ominus }{\mathrm{S}}\mathrm{H}$

Arrange the following in decreasing order of reactivity towards ${\mathrm{S}}_{\mathrm{N}}1$ reaction :-