In 1955, the Imperial Bank of India, then a leading commercial bank, was nationalised and renamed as which of the following banks?

Introduction / Context:
This question is drawn from Indian banking history and tests knowledge of how a major private bank was transformed into a large public sector bank. Understanding the origin of State Bank of India provides useful background for questions on public sector banking and financial sector reforms.

Given Data / Assumptions:

• The question specifies the year 1955.
• Imperial Bank of India was a leading commercial bank at that time.
• The bank was nationalised and renamed.
• Options list major Indian banks, one of which is the new name adopted after nationalisation.

Concept / Approach:
After independence, the government wanted a strong state owned bank to support development, handle government business and extend banking services throughout the country. The Imperial Bank of India, formed earlier through the merger of presidency banks, was an obvious candidate. In 1955 it was nationalised and renamed State Bank of India. The correct answer must therefore identify State Bank of India as the new name of the Imperial Bank after nationalisation.

Step-by-Step Solution:
Step 1: Recognise that the question asks specifically about the new name after nationalisation of the Imperial Bank of India.Step 2: Recall that State Bank of India is India largest public sector bank and traces its roots to the Imperial Bank of India.Step 3: Remember that in 1955, the government of India and the Reserve Bank of India took control of the Imperial Bank.Step 4: The bank was then officially renamed State Bank of India to reflect its new national role.Step 5: Match this information with the options and select State Bank of India as the answer.

Verification / Alternative check:
Banking history references and official State Bank of India publications clearly mention that the Imperial Bank of India was nationalised in 1955 and renamed State Bank of India. None of the other banks listed in the options has such a direct historical connection, which confirms the correctness of the choice.

Why Other Options Are Wrong:
Central Bank of India is a separate bank established earlier and was not formed by renaming the Imperial Bank.
Bank of India is also an independent commercial bank and does not share this origin.
Indian Bank is a different public sector bank primarily associated with the southern region.
Punjab National Bank has its own distinct history and was not created by renaming the Imperial Bank.

Common Pitfalls:
Candidates sometimes confuse the various nationalised banks because many were taken over during different phases of banking reforms. Another error is to think that the Reserve Bank of India changed its name, but that institution has always been the central bank, not a renamed commercial bank. Associating State Bank of India directly with Imperial Bank of India helps avoid such confusion.

Final Answer:
After nationalisation in 1955, the Imperial Bank of India was renamed State Bank of India.