Explanation:

- Neelam Sanjeeva Reddy served as Chief Minister from 1956 to 1959, making Option 1 - Chief Minister the correct answer.

- Reddy was the Chief Minister of Andhra Pradesh, the first after its formation from the merger of Andhra State and the Telangana region of Hyderabad State.

- Option 2 - President: Neelam Sanjeeva Reddy served as the President of India much later, from 1977 to 1982, not during the 1956-1959 period.

- Option 3 - Member of Rajya Sabha: He was primarily involved in legislative assemblies and the Lok Sabha before becoming President, rather than being a member of the Rajya Sabha during this time.

- Option 4 - Deputy Chief Minister: He served as Chief Minister, not Deputy Chief Minister.

- Correct Answer: Chief Minister.