Which amongst the following is NOT part of an informal letter?

The correct answer is Option (3) → The invoice

An invoice is a bill listing goods or services supplied and the amount to be paid. It belongs to business dealings, not to an informal letter written to a friend or relative.
Example: The shopkeeper sent an invoice for the furniture we had bought.

Why the Other Options are Incorrect?

Option 1: The address of the sender — Incorrect. An informal letter begins with the sender's address, followed by the date.

Option 2: The salutation or greeting — Incorrect. A greeting such as "Dear Riya" is a regular part of an informal letter.

Option 4: The signature — Incorrect. The letter ends with a closing such as "Yours lovingly" and the writer's name or signature.