The Government of India Act of 1919 clearly defined

1. A

   The separation of power between the judiciary and the legislature.

   (a) The separation of power between the judiciary and the legislature. GoI Act 1919 did not enact a US-style separation of those two organs. That is not what the Act ‘clearly defined’.

2. B

   The jurisdiction of the central and provincial governments.

   (b) The jurisdiction of the central and provincial governments. The 1919 Act (Montagu–Chelmsford) classified subjects and introduced dyarchy in the provinces, thereby drawing a clearer line between central and provincial jurisdiction. That is the official key.

3. C

   The powers of the Secretary of State for India and the Viceroy

   (c) The powers of the Secretary of State for India and the Viceroy. Those offices continued; 1919 did not newly and clearly recast that pair as its main definitional work in the sense of this question.

4. D

   None of the above

   (d) None of the above. Because (b) is correct, ‘none’ is wrong.

Summary. Official key is (b) The jurisdiction of the central and provincial governments. The Government of India Act, 1919 listed central and provincial subjects and introduced provincial dyarchy. It did not mainly define judiciary–legislature separation or recast Secretary of State versus Viceroy. The keyed content is the centre–province split.