Fine-tuning is the process of training a pre-trained LLM with a labeled dataset specific to a desired task—in this case, mapping user messages to JSON outputs. Fine-tuning leverages supervised learning to specialize the model’s outputs.

C is correct:

“Fine-tuning is a supervised learning approach in which a model is further trained on a custom, labeled dataset to adapt to a specific use case.”

(Reference: Amazon Bedrock Fine-Tuning, AWS Certified AI Practitioner Study Guide)

A is incorrect—unsupervised learning does not use labeled data.

B (continued pre-training) uses unlabeled data.

D (RLHF) uses reward signals and human feedback, not direct labeled input/output pairs.