What is it not true about formal letter writing?

Q: What is it not true about formal letter writing?

A) With a formal letter it is always best to keep the content as succinct and professional as possible in clear paragraphs. | B) There are many acceptable ways to end a formal letter; some examples being, "Thanks", "Hugs" and even "Love from" – depending on who you are writing the letter to and your relationship with that person. | C) No contractions should be used to simplify words. Abbreviations must be spelt out in full when first used, the only exceptions being when the acronym is better known than the full name such as BBC or NATO. | D) The greeting of the letter needs to be simply "Dear Sir or Madam" or if you know the name of the person to whom you are writing, then always write the greeting with the title, for example, "Dear Mrs Smith".