Cloud computing is a _______ system and it is necessarily unidirectional in…

A 'stateless' system treats every request as a complete, independent transaction — it retains no memory of earlier interactions once each one finishes. A 'stateful' system does the opposite: it deliberately keeps track of an ongoing session or context across multiple exchanges.

This exam item pairs two descriptors — "stateless" and "necessarily unidirectional in nature" — as characterizing cloud computing (and, more broadly, the plain HTTP/web request-response model the Internet runs on): each client request is handled as a fresh, self-contained transaction, with the server never retaining context or pushing information back on its own outside of a request it received. The accepted key for this item, matching the exam's official answer and multiple independent references, is "stateless" — the option describing exactly that request-driven, non-session-retaining behaviour. (Statelessness and unidirectionality are two separate descriptors used together here by the source material rather than one strictly implying the other in a rigorous technical sense; "stateless" remains the term this question — and its official key — is asking for.)

• stateful describes a system that retains context between exchanges — a real design used elsewhere, but not the one that fits an inherently one-way, independent-request model.

• reliable is a quality attribute (continuing to function despite failures), not an architectural description of how requests are handled, so it cannot fill this blank.

• all of the mentioned cannot be right because two of the listed terms are direct opposites of each other; a single system cannot be characterized by contradictory descriptions at once.