Important Battles question: The Battle of Saraighat (1671) was a naval battle fought on which river?

The verified answer to “Important Battles question: The Battle of Saraighat (1671) was a naval battle fought on which river?” is Brahmaputra, option B. The source-backed, question-specific record explains: The Battle of Saraighat was fought on the Brahmaputra River in 1671 between the Ahom Kingdom (under Lachit Borphukan) and the Mughal forces (under Ram Singh I). This evidence establishes the historical relationship required in this Important Battles item. A correct solution must preserve the exact battle, date, participants, commander, location, outcome or significance requested by the stem. Similar periods, genres or national traditions do not make two battle facts interchangeable. Option B gives Brahmaputra and satisfies every condition stated in the question. The remaining choices—Ganga, Godavari and Mahanadi—do not satisfy the complete requirement. The reliable checking method is to identify the named battle first, recall or verify its verified participant or outcome, and then read qualifiers such as “both works,” “original language,” “first published,” “correctly matched” or “incorrectly matched.” These qualifiers determine what counts as the answer. Replaying that method for this Important Battles question confirms Brahmaputra without relying on option position.