All mutations may not be deleterious. few beneficial mutations will provide a basis for possible differential propagation of the variation, and so of the evolutionary process. b. evolution can occur without inherited variation for adaptive traits; therefore mutation does not contribute significantly to evolution. c. most mutations are deleterious and there is little evidence demonstrating mutations have contributed to the evolutionary process. d. most mutations are deleterious. to prevent diseases due to mutation humans product drugs which affect healthy cells and cause their evolution. e. actually all mutations are deleterious. an organism with fewer mutations survives in evolutioonary process.