The verified answer to “Important Battles question: The Battle of Plassey (1757) was fought between the British East India Company and whom?” is Siraj ud-Daulah, option B. The source-backed, question-specific record explains: The Battle of Plassey was fought on June 23, 1757, between the British East India Company (led by Robert Clive) and the Nawab of Bengal, Siraj ud-Daulah. The British won due to the treachery of Mir Jafar. 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 Siraj ud-Daulah and satisfies every condition stated in the question. The remaining choices—Hyder Ali, Mir Qasim and Tipu Sultan—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 Siraj ud-Daulah without relying on option position. This approach builds accurate historical knowledge and careful option elimination for SSC, Railway, Banking, Defence, State and other competitive examinations.