Mopin is an agricultural festival celebrated by the Galo tribe in Arunachal Pradesh. It marks the beginning of sowing season and is a significant event for the community.
Losar is actually the Tibetan New Year, celebrated mainly in Ladakh region.
Ugadi is an agricultural festival celebrated by Kannada-speaking communities primarily in Karnataka, not Arunachal Pradesh.
Karma is not a known festival related to agriculture or the Galo tribe.
Therefore, Mopin stands out as the correct answer among the given options.