Which of the following best describes a business letter?

A business letter is best described as a formal written communication for professional purposes. This type of letter typically adheres to specific formatting and language conventions, ensuring clarity and professionalism. It is used to convey important information, requests, or responses in a structured manner that reflects the seriousness and intent of the communication. This formal nature distinguishes business letters from informal messages, such as casual communication between colleagues, which may not follow a specific structure or tone.

The requirement for multiple signatures pertains to certain business documents, but this does not define a business letter itself. Signatures are not a universal characteristic of all business letters, as many can be sent without requiring signatories. Similarly, a summary of market trends represents a more analytical or reporting type of document, which does not align with the defined characteristics and purpose of a business letter.