Which statement correctly differentiates synchronous vs asynchronous communication?

• A. Synchronous requires both parties present; asynchronous uses queues/events.
• B. Synchronous uses queues; asynchronous uses direct calls.
• C. Synchronous is always slower.
• D. Both are real-time.

Answer: (A)

Synchronous vs asynchronous communication mainly hinges on timing and coupling: in a synchronous interaction, both sides are engaged at the same time and the caller typically waits for a response before continuing. In contrast, asynchronous communication decouples the sender from the receiver, often using a queue or an event mechanism, so the sender can proceed without waiting and the message is processed later.

The statement that differentiates them well captures this: synchronous requires both parties present, while asynchronous uses queues or events. That combination reflects real-time, blocking interaction versus decoupled, non-blocking processing. It's not about one always being slower or about real-time being required in both cases; asynchronous can be non-blocking and may not be real-time, while synchronous is commonly real-time but not inherently slower by definition.