Answer:
Option D, Gene Pool
Explanation:
A Gene pool is just a data base of all available genes of any specific species with in a set of population . It no where talks about genetic change/ evolution of an species in the population.
Mutation is the change in the base pair (nucleotide bases) of a DNA, Natural selection is the way by which an species evolve and genetic drift is the change in existing genes due to random sampling of species.
Among all given options, option D (gene pool) is not a mechanism for evolution
Hence, option D is the correct answer.
