__________ testing focuses on the system as a whole.

• A. Unit
• B. Integration
• C. Module
• D. System

Answer: (D)

System testing examines the entire, integrated product in an environment that resembles production to verify that all parts work together and meet the overall requirements. It goes beyond testing individual pieces to assess end-to-end workflows, interactions between components, and nonfunctional qualities like performance, security, and usability. This is why it best fits the statement about focusing on the system as a whole. By contrast, unit testing targets small, individual components in isolation; module testing concentrates on a single module or a closely related set of functionalities; and integration testing checks how separate components interact with each other.