The people of India agitated against the arrival of Simon Commission because

The answer is C. The Simon Commission (Indian Statutory Commission, set up in 1927 under Sir John Simon) had seven members, all British MPs, and no Indian member. Indians saw this as a decision about their own future made without them, which is why the cry of 'Simon Go Back' was raised across the country when it arrived in 1928. The boycott was about the process and the exclusion, not about its recommendations.

• A is wrong. The 1919 Act itself provided for a review after ten years, and Indian leaders wanted a say in that review. Their objection was to who conducted it.
• B is wrong as a cause. The Commission did propose ending dyarchy in the provinces, but that was a recommendation in its report, which came later. People were not protesting over it when the Commission arrived.
• D is wrong. The Simon Commission did not suggest partitioning the country. Partition was not on its agenda.

Core concept: the constitutional development of British India, from the 1919 Act through the Simon Commission, the Nehru Report of 1928 and the Round Table Conferences. For Mains, this is a good example of how Indian demands for self-determination shaped constitutional reform.

Trap: Aspirants pick B because they remember the dyarchy recommendation. But a question on the cause of an agitation needs the reason people reacted at the time, not what the report later said.