Which principle most improves testability and maintainability in an MIPC software project?

• A. High coupling and shared state
• B. Low cohesion and tightly coupled modules
• C. High cohesion and low coupling
• D. Monolithic architecture with no interfaces

Answer: (C)

Designing for high cohesion and low coupling makes testability and maintainability much easier. High cohesion means each module has a clear, focused responsibility and all of its parts work together toward that purpose. This tight, single-minded focus helps you understand what the module does, write precise unit tests for its behavior, and locate bugs quickly. Low coupling means modules depend on each other as little as possible, usually through well-defined interfaces or abstractions. Loose connections let you test a module in isolation, replace or modify parts without second-order effects, and evolve the system without cascading changes. When modules are highly cohesive and loosely coupled, changes are easier to reason about, tests stay reliable, and the codebase remains adaptable. In contrast, strong interdependencies, shared mutable state, or a monolithic design with no interfaces raise complexity, cause brittle tests, and make maintenance a headache.