The correct option is D All of the above
Organic nitro compounds exhibit chain isomerism ,positional isomerism ,Functional isomerism and tautomerism
Ex:1-nitro butane and 2-methyl 1-nitro propane are chain isomers
1-nitro propane and 2-nitro propane.Positional isomers
Methyl nitrate and nitro methane are functional isomers
In solution the nitro form is in equilibrium with azinitro form.(Tautomerism)
Hence option D is correct