Explanation:

- Correct Answer: Option 3 - S Somanath

- S Somanath was appointed as the Chairman of the Indian Space Research Organisation (ISRO) in January 2022. He succeeded K Sivan, becoming the 10th Chairman of the organization. Prior to his appointment, Somanath served as the Director of the Vikram Sarabhai Space Centre (VSSC).

- Option 1: K Radhakrishnan

- K Radhakrishnan served as the Chairman of ISRO from 2009 to 2014. During his tenure, India launched the Mars Orbiter Mission (Mangalyaan).

- Option 2: K Sivan

- K Sivan served as the Chairman of ISRO from 2018 until January 2022. He was instrumental in several key initiatives, including the Chandrayaan-2 mission.

- Option 4: G Madhavan

- G Madhavan Nair served as the Chairman of ISRO from 2003 to 2009, contributing significantly to India's space program during his tenure.