The correct option is C Mutations together with natural selection
According to neo-Darwinism, mutations produce sudden, discontinuous variations which accumulate in the gene pool. These random variations are acted upon by natural selection that favors, through differential reproduction, only those which confer survival and/or reproductive advantage to the individuals over others. Accumulation of these adaptive variations in lineages over generation makes them better adapted to existing environmental conditions. Further, reproductive isolation of populations of species by geographical and/or physiological barriers leads to the formation of new species i.e. evolution. Mutations and hybridization accumulate genetic variations, the raw material on which natural selection acts upon to select the useful variation. The correct answer is C.