The correct answer is Members of a Trade Union.

• A pressure group is an organised group of people which are active in pursuing common interests.
• Pressure groups try to bring a change in public policy by exerting pressure on the government.
• The pressure groups are also called interest groups or vested groups.
• They do not have direct political party power.
• They are concerned with specific programs and issues and their activities are confined to the protection and promotion of the interests of their members by pressuring the government.
• The pressure groups influence the policy-making in the government through legal and legitimate methods like lobbying, correspondence, publicity, propagandising, petitioning, public debating, legislations, etc.

•  Business Groups:
  • FICCI
  • ASSOCHAM etc
• Trade Unions:
  • AITUC
  • INTUC
  • Bharatiya Mazdoor Sangh (BMS)
• Professional Groups:
  • Bar Council of India (BCI)
• Agrarian Groups-
  • All India Kisan Sabha
  • Bharatiya Kisan Union etc
• Student’s Organisations:
  • Akhila Bhartiya Vidyarthi Parishad (ABVP)
  • All India Students Federation (AISF)
  • National Students Union of India (NSUI)
• Religious Groups:
  • Rashtriya Swayam Sevak Sangh (RSS),
  • Vishwa Hindu Parishad (VHP),
  • Jamaat-e-Islami, etc.

• Linguistic Groups:
  • Tamil Sangh
  • Tribal Groups – National Socialist Council of Nagaland (NSCN)
  • Tribal National Volunteers
  • Tribal League of Assam, etc.
• Ideology based Groups:
  • Narmada Bachao Andolan
  • Chipko Movement.
• Anomic Groups:
  • Naxalite Groups
  • United Liberation Front of Assam (ULFA) 

• Types of Pressure Groups:
  • Institutional Interest Groups
  • Associational Interest Group
  • Non-Associational Interest Groups
  • Anomic Interest Groups