Explanation:

1 and 4 only

It introduced, for the first time, bicameral legislature at the centre.

Correct. The Government of India Act 1919 introduced a bicameral legislature at the central level with the introduction of the Council of States (Council of State and Legislative Assembly).

It for the first time allowed members to discuss the budget and criticize the financial policy of the government.

Incorrect. The Act did not introduce this provision. Members were allowed to discuss the budget, but significant financial powers remained with the executive.

It made provincial legislature of Bengal and United Province bicameral.

Incorrect. The Act made the legislatures of Bombay, Madras, and the Punjab bicameral, but not Bengal and the United Provinces (now Uttar Pradesh).

It divided the provincial subjects into two parts—transferred and reserved.

Correct. The Act introduced the concept of dividing provincial subjects into two parts—transferred and reserved. Transferred subjects were to be administered by ministers responsible to the legislature, while reserved subjects remained under the direct control of the governor.

Therefore, the correct answer is 1 and 4 only.