A Parliamentary System of Government is one in which

(a) all political parties in the Parliament are represented in the Government
(b) the Government is responsible to the Parliament and can be removed by it ✓ UPSC's answer
(c) the Government is elected by the people and can be removed by them
(d) the Government is chosen by the Parliament but cannot be removed by it before completion of a fixed term

Why the answer is (b)

• The defining feature of a parliamentary system is collective responsibility: the executive (Council of Ministers) is drawn from and answerable to the legislature and can be removed by a vote of no confidence — option (b); Article 75(3) embodies this in India.

• Option (a) describes a national/all-party government, not the system itself.

• Option (c) describes the presidential system, where the executive is elected directly and is not removable by the legislature except by impeachment.

• Option (d) mixes the two: a fixed-term, non-removable executive is presidential, not parliamentary.

• Hence option (b).

Why the other options are wrong

(a) all political parties in the Parliament are represented in the Government: All-party representation is not a feature of the parliamentary system.
(c) the Government is elected by the people and can be removed by them: Direct election and removal by the people describe a presidential system.
(d) the Government is chosen by the Parliament but cannot be removed by it before completion…: A fixed, non-removable term is presidential, not parliamentary.

Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2020, held on 4 October 2020. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.