Given the complexity of individuals' lives and the multifaceted nature of the problems that clients experience, social workers need knowledge in which area?

Politics, economics and biology.

Explanation:

Exercising social work implicates a wide variety of psychosocial services to persons, familiar groups, and small groups related to a diversity of human problems in their lives. Social work takes place both in public and private contexts. It concerns an evaluation of interaction within a person's biological, psychological, political, and social experiences, which gives the professional a guide to intervening clinically.