Explanation:

- 1969: In this year, the Indian government nationalized 14 major private banks. This step aimed to control the commanding heights of the economy and enhance banking penetration. However, this was not a comprehensive reform.

- 1981: No major banking sector reform in this year. Some policy changes might have occurred, but nothing significant as a reform.

- 1991: The banking sector reforms began in earnest as part of the broader economic liberalization initiated by the government. It aimed to make banks more efficient and competitive.

- 2001: This year saw technological advancements and consolidation in the banking sector but not initial reforms.