In mung bean, resistance to yellow mosaic virus and powdery mildew were induced by:

Mutation

The correct answer is Option (4) - Mutation

Mutation is the process by which genetic variations are created through changes in the base sequence within genes resulting in the creation of a new character or trait not found in the parental type. It is possible to induce mutations artificially through use of chemicals or radiations (like gamma radiations), and selecting and using the plants that have the desirable character as a source in breeding – this process is called mutation breeding. In mung bean, resistance to yellow mosaic virus and powdery mildew were induced by mutations.