Which of the Following Are True of the Postal Rule

Which of the following are true of the postal rule of acceptance?

A) Parties can exclude the operation of the rule if they choose
B) It does not apply if the letter is in any way delayed in the post
C) It applies even where the offeror specifies that they will not accept acceptance by post
D) It applies only where postage would be an appropriately speedy means of replying to an offer