Final answer:
In the Linnaean system of biological taxonomy, an order is composed of several related families.
Step-by-step explanation:
An order in the context of biological taxonomy is composed of a number of related families. The hierarchy of biological organization is such that each level encompasses a broader category of organisms. The hierarchical classification system, known as the Linnaean system, is structured from most inclusive to most specific as follows: domain, kingdom, phylum, class, order, family, genus, and species. Therefore, the correct answer to the question is 'families'.