For the reaction `N_2O_4 hArr 2NO_2(g)`, if percentage dissociation of `N_2O_4` are 20%, 45%, 65%, 80% then the sequence of observed vapour densities wil be :
A. `d_(20)gtd_(45)gtd_(65)gtd_(80)`
B. `d_(80)gtd_(63)gtd_(45)gtd_(20)`
C. `d_(20)=d_(45)=d_(65)=d_(80)`
D. `d_(2)=d_(45)gt d_(65)=d_(80)`