True Statements About Demand Letters Include Which of the Following

True statements about demand letters include which of the following?

A) The language should be forceful and harassing.
B) The client's demand must not be frivolous.
C) The letter should be insistent and adversarial.
D) The client's demand must not be frivolous, and the letter should be insistent and adversarial.
E) The language should be forceful and harassing, the client's demand must not be frivolous, and the letter should be insistent and adversarial.