a. An agency for widening the scope of parliamentary democracy

b. An agency for strengthening the structure of federalism

c. An agency for facilitating political stability and economic growth

d. An agency for the implementation of public policy.

Answer- d

Explanation:

Public administration is mainly a policy implementation organisation. Many other actors such as legislature, courts, pressure groups, and community organisations help the process. 

In a modern political system, a public policy is implemented primarily by a complex system of administrative agencies. These agencies perform most of the day-to-day work of government and thus affect citizens directly in their actions. 

Administrative agencies often operate under broad and ambiguous statutory mandates that leave them with much discretion to decide what should or should not be done. Lack of time, interest, information, and expertness on the part of politicians may also contribute to the delegation authority to these agencies. Policy implementation is not an easy task. Without the cooperation of top administrators, little can be achieved.

Hence, option d is correct.

Read: Previous Year UPSC Polity Questions (PYQs) With Explanation 2020