Membership of pressure groups is usually limited because they
The correct answer is: A
Explanation
Pressure groups often have limited membership because they focus on specific and narrow objectives. These groups are formed around particular issues or causes, and their appeal may be limited to individuals who are particularly interested in or affected by those issues. This focus helps them to concentrate their efforts and resources effectively, but it also means that their membership base tends to be smaller and more specialised compared to broader organizations.