Step 1: Question Overview:
The question identifies a central government program from 2000 offering free food grains to impoverished senior citizens.
Step 2: Scheme Analysis:
Annapurna Scheme (APS): Launched April 1st, 2000, by the Ministry of Rural Development. It supports destitute senior citizens (65+) not covered by the National Old Age Pension Scheme (NOAPS). This scheme provides 10 kg of free food grains monthly per person, fully meeting the question's criteria (2000, indigent seniors, free food).
Integrated Older Persons Scheme: This program offers financial aid to organizations for facilities like old age homes; it does not directly provide food grains.
Antyodaya Anna Yojana (AAY): Introduced in December 2000, this scheme provides heavily subsidized food grains to the poorest families, not exclusively senior citizens. The grains are subsidized, not free.
Annaposhan Vridha Yojana: This is not a recognized central government scheme.
Step 3: Conclusion:
The Annapurna Scheme is the program providing free food grains to indigent senior citizens.