Who is the only Speaker of the Lok Sabha who later went on to become the President of India?

Introduction / Context:
Indian constitutional history includes several distinguished leaders who have held more than one high constitutional post. The Speaker of the Lok Sabha is the presiding officer of the lower house, while the President of India is the head of state. It is therefore a notable fact when one person has occupied both roles. This question asks about the only leader who first served as Speaker of the Lok Sabha and later became President of India, which is a favourite factual point in polity and general knowledge exams.

Given Data / Assumptions:

• The focus is on someone who has been both Lok Sabha Speaker and later President.
• Options list several presidents and senior leaders.
• We need to recall their earlier positions before they became President.

Concept / Approach:
Neelam Sanjiva Reddy was the first person to be elected unopposed as President of India and is also remembered as a former Speaker of the Lok Sabha. He served as the sixth Speaker of the Lok Sabha before assuming the office of President. Other leaders in the options also became President, but they did not serve as Speaker of the Lok Sabha. To answer correctly, we link each name with their primary constitutional roles and eliminate those who never held the Speaker office.

Step-by-Step Solution:
Step 1: Recall that Neelam Sanjiva Reddy was Speaker of the Lok Sabha in the early years after independence.Step 2: Remember that he later became President of India and was elected to that post without any rival candidate.Step 3: Check the other options. V V Giri served as Vice President and then President but was not Speaker.Step 4: Zail Singh was a former Chief Minister and Union Home Minister, not Speaker.Step 5: S Radhakrishnan and Pranab Mukherjee held other high offices but never served as Speaker of the Lok Sabha. Therefore the only correct option is Neelam Sanjiva Reddy.

Verification / Alternative check:
An alternative confirmation is to review the list of Speakers and Presidents in standard polity books. Among all Presidents listed, only the name of Neelam Sanjiva Reddy appears in the list of former Speakers. Additionally, exam guides often highlight him with the special note that he was elected President unopposed, which is another unique fact associated with him. Matching this with the historical record confirms that no other name in the options satisfies both conditions.

Why Other Options Are Wrong:
V V Giri was the fourth President of India and earlier served as Vice President, but he did not chair the Lok Sabha as Speaker. Zail Singh was a former Chief Minister of Punjab and Union Home Minister. S Radhakrishnan was a philosopher and served as Vice President and then President. Pranab Mukherjee held offices like Finance Minister and External Affairs Minister, later becoming President, but he was never Speaker. Hence, these names do not match the combination asked in the question.

Common Pitfalls:
Many learners confuse the posts of Speaker and Vice President because both have roles in the Parliament. Another common mistake is to assume that popular Presidents like S Radhakrishnan or Pranab Mukherjee must have held all major offices. The safest approach is to memorise one or two unique facts about each President. For Neelam Sanjiva Reddy, the key facts are his unopposed election and his earlier role as Speaker of the Lok Sabha.

Final Answer:
Neelam Sanjiva Reddy