Final answer:
The functionalist theory explains how social institutions in Nigeria work together to maintain the whole society by meeting the biological and social needs of individuals.
Step-by-step explanation:
The functionalist theory, also known as structural-functional theory, views society as a structure with interrelated parts designed to meet the biological and social needs of individuals. In Nigeria, social institutions such as government, education, family, healthcare, religion, and the economy work together to maintain the whole society. For example, the government ensures law and order, the education system provides knowledge and skills to the workforce, and the economy ensures the distribution of goods and services. By functioning harmoniously, these institutions contribute to the stability and cohesion of Nigerian society.