Identify the part of the sentence that contains a grammatical error: Though there is progress (a) / for different directions, (b) / why is there no brotherhood? (c) / No error (d)

The Dandi March, also known as the Salt Satyagraha, was led by which influential leader?

Which act formally granted independence to India, marking the end of British rule?

Who was the key figure in establishing the Indian National Congress?