The option that can be used as a one-word substitute for the given group of words "One who has the ability to do many different things" is "Versatile."

Explanation of the options:

☀ Versatile: This word describes someone who is capable of adapting or performing well in various different tasks or roles.

☀ Adaptable: This word also describes someone who is capable of adjusting or changing to different situations or tasks, but it may not necessarily imply a wide range of abilities.

☀ Expert: This word refers to someone who has extensive knowledge, skill, or proficiency in a particular field or subject.

☀ Specialist: This word refers to someone who has specialized knowledge or skill in a specific area or field, but it does not necessarily imply the ability to do many different things.