Q.Optional functions of government:
Protection from external attack
Provision of education and health services
Provision of social security measures
Collection of tax

The obligatory function of government is maintaining internal law and order, so the answer is only b.

Government functions are divided into obligatory (compulsory) functions — those the State must perform to exist, such as defence, justice, and maintaining internal law and order — and optional (welfare) functions it performs to raise citizens' welfare.

• (b) Maintaining internal law and order is a classic obligatory function. …

Government functions are grouped into obligatory (must be performed) and optional (performed for public welfare). Provision of education and health services (b) and social security measures (c) are optional welfare functions. Defence from external attack (a) and tax collection (d) are obligatory. Correct option: b and c.

Why: Following the modern welfare-state view of public finance, government duties fall into two classes:

• Obligatory functions — the basic, unavoidable duties of any state: defence against external attack, maintenance of law and order, and administration of justice; raising revenue through taxation to finance these is equally compulsory. …