20. Which situation fails the study guide's test for independence?
- 1A developer can specify a module's output without referring to another module's internal logic.

- 2A service can be plugged into the system through an API with limited dependence on other components.

- 3A component can only be defined by referring to the inputs and internal workings of several other components.

- 4A feature can be added without redesigning the rest of the system.
