What is continued pre-training?

Comprehensive and Detailed Explanation From Exact AWS AI documents:

Continued pre-training involves training an already pre-trained model further using unlabeled, domain-specific data.

AWS generative AI guidance explains that continued pre-training:

Expands domain knowledge

Preserves general language understanding

Differs from fine-tuning, which uses labeled data

Why the other options are incorrect:

A describes fine-tuning.

C describes training from scratch.

D describes evaluation.

AWS AI document references:

Foundation Model Customization Techniques

Continued Pre-Training vs Fine-Tuning

Domain Adaptation on AWS