In the context of Indian history, the principle of 'Dyarchy (diarchy)' refers to
Explanation
Dyarchy, introduced by the Government of India Act 1919, refers to the division of provincial subjects into two categories—'Reserved' and 'Transferred'—to be administered by the Governor and his ministers respectively. Option (a) is a common distractor because it describes 'bicameralism' (two houses of legislature), which was also introduced in 1919 but is distinct from the executive power-sharing defined by dyarchy. The core concept being tested is the evolution of administrative and constitutional reforms under the British Raj, specifically the Montagu-Chelmsford Reforms.