The correct option is (a).
Explanation
The political causes of the Revolt of 1857 were rooted in the aggressive expansionist policies of the East India Company and the systematic erosion of the authority and dignity of traditional Indian rulers, particularly the Mughal Emperor.
Statement 1 is Correct: The Subsidiary Alliance was imposed on Awadh by Lord Wellesley in 1801. Under the terms of this alliance, the Nawab was compelled to disband his military force, accept a British Resident, and cede approximately half of his territory (including Rohilkhand and the Lower Doab) to the Company for the maintenance of British troops.
Statement 2 is Incorrect: Governor-General Canning did not declare that the title of King would continue. On the contrary, in 1856, Canning announced that Bahadur Shah Zafar would be the last Mughal King and that after his death, his descendants would be recognized only as princes, thereby abolishing the regal title.
Statement 3 is Incorrect: The East India Company removed the name of the Mughal Emperor from its coins in 1835. This occurred more than two decades before the Revolt of 1857 and was a symbolic assertion of British sovereignty, signaling that they no longer recognized the Emperor's suzerainty.
Key Takeaway: The British policy of diminishing the Mughal Emperor's status, marked by the removal of his name from coinage (1835) and the decision to abolish the royal title (1856), created deep resentment and was a primary political cause of the Revolt of 1857.