How do you create a new database in MongoDB?

Creating a new database in MongoDB primarily occurs automatically when data is inserted into a collection. In MongoDB, when you attempt to insert a document into a collection that does not exist, the MongoDB server automatically creates the database and the collection for you. This behavior allows for a flexible and dynamic way to manage databases and collections, accommodating the needs of applications without requiring pre-defined schemas or explicit creation commands.

The other methods mentioned, such as writing commands in the shell, using a visual interface tool, or adjusting server configuration files, do not reflect the inherent design of MongoDB where the system handles database initialization on demand when data operations are performed. Therefore, option B accurately captures the nature of how databases are created within the MongoDB environment.