Zero-shot Chain-of-Thought prompting encourages a language model to decompose a problem into intermediate reasoning steps without supplying worked examples in the prompt. The classic prompting addition associated with this technique is “Let's think step by step.” The technique is “zero-shot” because the user does not provide demonstrations showing how comparable problems should be solved; instead, a short natural-language instruction encourages stepwise decomposition.

OpenAI's published prompting guidance historically illustrates this exact technique, explaining that instructing a model to reason through a sequence of steps can improve performance on tasks requiring decomposition. The OpenAI Cookbook specifically gives “Let's think step by step” as an example of an instruction used to elicit a series of reasoning steps.

Setting temperature to zero affects sampling variability rather than creating Chain-of-Thought prompting. Uploading structured data is unrelated to the reasoning technique, and disabling retrieval tools changes the model's information-access environment rather than prompting its problem-solving structure.

Accordingly, C is the intended and technically correct answer. The uploaded source also marks this exact phrase as correct.

Study Guide reference/topic: Introduction to AI Agents — prompting strategies, reasoning decomposition, zero-shot Chain-of-Thought, and agent reasoning patterns.

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