Where did Mangal Pandey fire the first shot of the Revolt of 1857?

Consider the following statements regarding the Revolt of 1857: (a) The 1857 Revolt began at Meerut on 10 May, 1857. (b) At Kanpur, the revolt was led by Nana Saheb. (c) At Lucknow, the revolt was led by Begum Hazrat Mahal. (d) At Bihar, the revolt was led by Kunwar Singh. Which of the statements given above are correct?

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: The Revolt of 1857 was characterized by a multi-causal effort to dismantle the structural foundations of the British Raj and restore the sovereignty of the Mughal Emperor. Reason R: Historiographical analysis reveals that the insurrection was ultimately unsuccessful because it lacked a coordinated all-India command structure and failed to gain the participation of English-educated professionals and major princely states like Hyderabad and Patiala. In the light of the above statements, choose the most appropriate answer from the options given below: