Which of the following is not included in a formal letter?

The correct answer is Option (3) → With lots of love

With lots of love is an affectionate closing used in informal letters to family and friends. A formal letter keeps a polite, impersonal tone and closes with "Yours faithfully" or "Yours sincerely", so this expression has no place in it.

Why the Other Options are Incorrect?

Option 1: Subject — Incorrect. Correct use: the subject line states the purpose of the letter in a few words; it is a regular part of a formal letter.

Option 2: Salutation — Incorrect. Correct use: the salutation (Sir / Madam, Dear Sir) is the greeting at the start of every formal letter.

Option 4: Date — Incorrect. Correct use: the date is written below the sender's address in every formal letter.