Solution

Morgan and Sturtevant worked on Drosophila and gave the chromosomal theory of heredity. Uniparental inheritance creates asexual lineages that are vulnerable to mutation accumulation, it was termed as “ratchet” by Muller. Hugo de Vries coined the term “mutation” to refer sudden random changes in genetic material. Darwin considered variations as an inherent property of virtually every group of animals and plants. Biotic potential leads to overproduction of offspring but the struggle for reproduction and survival put a check on population density allowing only surviving individuals to pass on their genes in greater proportion. Thus, the appearance of favourable changes in genetic material, the “sport”, are passed to next generation which favoured by natural selection. Therefore, the correct answer is option C.