Concept:The main distinguishing feature between a political party and a pressure group is their purpose or aim.Explanation:A political party seeks to win elections and gain political power to govern.A pressure group does not seek to govern; it only tries to influence those who hold power.Political parties deal with a wide range of national issues, while pressure groups focus on narrow or specific interests.Therefore, the essential difference lies in their objectives, not their organization, strategy, or source of finance.Answer:A. Objective