Benzene = hexadeutrobenzene < Toulene

 

Nitration is an electrophilic substitution reaction which involves NO₂⁺ ion.
In case of toulene, there is an electron releasing group, -CH₃ and thus it facilitates nitration.
Substitution of H by its isotope D doesn't have any effect on nitration. So benzene and hexadeutrobenzene have same rates of nitration.