Following is a list of evidence to support Darwinism,...

Darwinism is supported by many evidences such as the evolution of the long-necked giraffe through survival of the fittest, the development of DDT resistance in mosquitoes, and industrial melanism (evolution of black-coloured moths).

However, the existence of neutral flowers and the sterility of hybrids are considered classic objections to Darwinism. Natural selection operates on traits that enhance reproductive success, so the development of sterile hybrids and neutral (sterile) flowers cannot be easily explained by Darwin's original theory.

Answer: existence of neutral flowers and sterility of hybrids