The correct answer is option D
Organic compounds are broadly classified into open chain and closed chain compounds. Explanation: open chain compounds or acyclic compounds are otherwise called as aliphatic compounds.

Open chain compounds or acyclic compounds are otherwise called as aliphatic compounds.

Cyclopropane is a ring (cyclic) compound and hence it does not come with the examples of open chain compounds.

Acetic acid is a linear chain compound (acyclic) and hence it is not an example of ring compound (alicyclic).

Pyridine is heterocyclic aromatic compound. Whereas naphthalene and aniline are benzenoid aromatic compounds and tropolone is a non-benzenoid aromatic compound.

Branched chain compound is a classification of open-chain compounds. Whereas, alicyclic, aromatic and heterogeneous compounds are sub-classifications of cyclic compounds.

Azulene is a non- benzenoid compound. Whereas, Indene, anthracene, and o,m,p-Xylene are examples of benzenoid aromatic compounds.

Isocyanide is a compound and it is not a functional group.

Classes of organic compounds are those which involves organic compounds such as carbon, hydrogen and oxygen. Hence, electro compounds is not a class of organic compounds.

The aromatic compounds (4n+2)pi electrons, which comes under the classification of cyclic compounds and hence they are not associated with aliphatic compounds.