NIMBLE
- agile (correct answer)
- clumsy
- simple
- strong
Explanation: The word NIMBLE means quick and light in movement or action. The word 'agile' has the same meaning. Therefore, 'agile' is the correct synonym. 'Clumsy' is an antonym. A person can be 'strong' without being nimble, and 'simple' is an unrelated quality.