Which of the following describes the data stored in MongoDB documents?

The data stored in MongoDB documents is best described by the choice that characterizes it as key-value pairs, similar to JSON. This is because MongoDB uses a document model where each document is a flexible, schema-less data structure that can contain various types of data organized in key-value pairs. This flexibility allows documents to have different fields and data types, all while maintaining the ability to accommodate complex nested structures.

This JSON-like format enables developers to easily interact with the data using familiar syntaxes, which is particularly advantageous for web and mobile applications where JSON is a common data interchange format. Therefore, the structure and nature of MongoDB documents make them highly suitable for storing and managing diverse and dynamic data.

The other options do not accurately reflect the functionality or structure of MongoDB documents. For instance, limiting data to only numeric values or defining rigid set configurations does not align with the flexible approach that MongoDB adopts. Similarly, describing entries as only static and unchanging neglects the dynamic capabilities of MongoDB to handle real-time data updates and modifications.