In the context of Indian history, what does the principle of ‘Dyarchy (diarchy)' refer to?

Dyarchy was introduced under the Government of India Act, 1919 (Montagu-Chelmsford reforms). Provincial subjects were split into two lists: reserved subjects such as finance, law and order, and land revenue, which stayed with the Governor and his executive council, and transferred subjects such as education, public health, local self-government and agriculture, which were handled by ministers responsible to the provincial legislative council. That division of subjects delegated to the provinces into two categories is what option D describes.

• A is wrong: the 1919 Act made the central legislature bicameral (Council of State and Legislative Assembly), but that is not dyarchy.
• B is wrong: a Central-State division is ordinary federal structure, not dyarchy.
• C is wrong: it is a fanciful reading with no constitutional basis.

The concept links to the Mains theme of constitutional development from the 1909 Morley-Minto reforms through 1919 to 1935, and to how responsible government was tested in the provinces. Dyarchy ended in 1937 when provincial autonomy under the Government of India Act, 1935 came into effect.

Trap: Aspirants confuse dyarchy with the bicameral centre or with the general Centre-State division. Remember that dyarchy means dual rule within a province, over the same set of subjects split into two.