The __________ may be able to specify style information for a particular document. For example, the user may specify a file that contains a style sheet or the user agent may provide an interface that generates a user style sheet.

The correct answer is B. user.

The user is the person who is reading or viewing the document. They may be able to specify style information for the document by using a style sheet or by using an interface provided by the user agent.

The author is the person who created the document. They may specify style information for the document in the document itself or in a separate style sheet.

The user agent is the software that is used to display the document. It may provide an interface that allows the user to specify style information for the document.

None of the mentioned is not the correct answer because the user is the one who can specify style information for a particular document.