Which of the following is NOT typically found in a business letter?

In a business letter, maintaining a formal and professional tone is essential. A casual tone is not typically found in these types of communications, as business letters are meant to convey information clearly and respectfully. The use of colloquial language or an informal approach can undermine the seriousness and professionalism expected in business correspondence.

On the other hand, the sender's contact information, recipient's address, and reference lines are standard components of a business letter. The sender's contact information ensures that the recipient knows how to reach them, while the recipient's address is critical for clear communication about who the letter is intended for. A reference line provides context or a subject for the letter, often helping the recipient understand the purpose of the correspondence immediately. These elements contribute to the overall effectiveness and professionalism of business letters, reinforcing the importance of well-structured communication in a business environment.