Final answer:
In a Zero capacity queue, the sender blocks until the receiver is ready to receive the message, which means there is no actual queuing of messages. This synchronization mechanism prevents the sender from sending messages that would wait in the queue, as there is no waiting area in such a model.
Step-by-step explanation:
In the context of queues in computer science, specifically relating to messaging systems or process synchronization, a Zero capacity queue is a conceptual model where the queue is designed to have no waiting area for messages.
Therefore, the correct statements are b) the sender blocks until the receiver receives the message, and not c) as zero capacity queues do not store messages for any duration; they act as a direct handoff point.