Key Indian political shifts in the 1990s comprised:
1. Economic Liberalization (1991): Led by P.V. Narasimha Rao, India enacted economic reforms like trade deregulation, privatization, and opening to foreign investment, propelling it to become a leading global growth economy.
2. Emergence of Coalition Governments: The period witnessed the formation of coalition governments at the national level, characterized by the increased influence of regional parties. This ended the Congress party's single-party dominance and amplified regional political voices.
3. Babri Masjid Demolition (1992): The destruction of the Babri Masjid by Hindu groups ignited significant communal unrest, leaving a lasting imprint on Indian politics, particularly concerning Hindu-Muslim relations.
Therefore, the accurate choice is (a).