Final answer:
An informal letter is a personal or friendly letter written to someone you know well, such as a friend or family member. Examples include letters to friends, thank you notes, and personal emails. The options 1 Timothy, 2 Corinthians, 2 John, and Philemon are all books from the New Testament and not examples of informal letters.
Step-by-step explanation:
An informal letter is a personal or friendly letter written to someone you know well, such as a friend or family member.
It is usually written in a conversational tone and does not follow strict rules of formatting and structure. Examples of informal letters include letters to friends, thank you notes, and personal emails.
In the given options, 1 Timothy, 2 Corinthians, 2 John, and Philemon are all books from the New Testament of the Bible and therefore not examples of informal letters.