The correct answer is: a) Indian nationalism.
The Revolt of 1857, also known as the Indian Rebellion of 1857, the Sepoy Mutiny, the Indian Mutiny, or the First War of Indian Independence, was a major uprising in India in 1857 against the rule of the British East India Company. The revolt began on 10 May 1857 at Meerut, and soon spread to other parts of northern and central India. The rebels were led by a number of different groups, including Indian soldiers, peasants, and religious leaders. The revolt was eventually suppressed by the British, but it had a profound impact on the history of India.
The Revolt of 1857 is seen by some historians as an early expression of Indian nationalism. This is because the revolt was a widespread uprising against British rule, and it was led by a number of different groups who were united by their common desire to overthrow the British. The revolt also had a significant impact on the development of Indian nationalism in the years that followed.
The other options are incorrect because they do not accurately describe the Revolt of 1857. Option b, communal conflict, is incorrect because the revolt was not primarily a conflict between Hindus and Muslims. Option c, regional separatism, is incorrect because the revolt was not primarily a conflict between different regions of India. Option d, class struggle, is incorrect because the revolt was not primarily a conflict between different social classes.