Which method focuses on breaking down complex business functions into simpler components?

Functional decomposition is a crucial method used in requirements analysis to simplify complex business functions. This technique involves breaking down large and intricate processes into smaller, more manageable components. By doing so, it allows analysts and stakeholders to better understand each individual function, its purpose, and how it relates to the overall system. This structured approach not only clarifies workflows but also enhances communication among team members, making it easier to identify requirements and pinpoint areas for improvement.

In contrast, the other options serve different purposes in the context of business analysis. A data dictionary provides a detailed description of data elements and their meanings within a system but does not focus on decomposing functions. Data modeling is concerned with representing data structures and their relationships rather than breaking down functions. Decision modeling focuses on the logic and rules governing decisions within a business process, which is a different aspect of analysis altogether. Each of these methods has its own importance, but when the goal is to simplify complex functions, functional decomposition is the most appropriate choice.