The correct option is D Salivary glands of Drosophila
Polytene chromosomes are giant chromosomes common to many dipterans (Drosophila) flies. Polytene chromosomes in salivary glands of Drosophila are formed as a result of the replication of the chromosomes and the synapsis of homologues without cell division. It is known as endomitosis. They begin as normal chromosomes, but through repeated rounds of DNA replication without any cell division, they become large banded chromosomes. Thus, the correct answer is option D.