The correct option is D Polyploidy
Changes in chromosome number by additions or deletions of less than a whole set is called aneuploidy. Monoploidy refers to the presence of a single basic set of chromosome. Polytene chromosomes are giant chromosomes having many parallel DNA duplexes as a result of the endo-reduplication and the synapsis of homologues without cell division. Polyploidy refers to the presence of more than two sets of chromosomes; diploid organism having multiples of 2n genome is polyploid. Thus, the correct answer is option C.