UPSC Civil Services Model Paper 5

New species are formed due to Geographical isolation, Genetic drift, Variation so variation is due to change in chromosome number . Hence statement (A) is correct.
Change of DNA in germ cell and due to change in genetic material . Hence statement (B) is correct.
Evolution will not take place without change and variation the genetic material.
Hence, the change in genetic material and variation in a chromosome is required for the evolution of new species.