Which architectural style structures a software system as a sequence of data-processing components where the output of one component serves as input to the next?
Option A is correct. Pipe and Filter architecture processes stream data by passing it through sequential independent filter components connected by pipes (e.g., UNIX shell pipelines).
Which architectural style organizes a software system into hierarchical tiers where each layer provides services to the layer above it and consumes services from the layer below?
Option B is correct. Layered (N-Tier) Architecture separates concerns into horizontal layers (e.g., Presentation, Business Logic, Data Access), enforcing strict top-down service invocation.
Which Gang of Four (GoF) creational design pattern ensures that a class has only one single instance throughout the application lifecycle and provides a global access point to it?
Option C is correct. The Singleton Pattern restricts object creation so that only a single instance exists, offering a central global access point.
Which GoF structural design pattern allows objects with incompatible interfaces to collaborate by converting the interface of one class into another interface expected by clients?
Option A is correct. The Adapter Pattern acts as a wrapper between two incompatible interfaces, enabling them to communicate smoothly without changing existing source code.
Which GoF behavioral design pattern defines a one-to-many dependency between objects such that when one object changes state, all its dependents are notified automatically?
Option B is correct. The Observer Pattern establishes a publish-subscribe mechanism where subject state changes automatically notify and update all registered observer objects.