15. Which of the following statements concerning delay is incorrect?*

(A) there is no delay in obligations not to do.

(B) as a rule, delay exists when the debtor does not perform his obligation on due date.

(C) as a rule, demand is required in order for delay to exist.

(D) when time is of the essence of the contract, delay on the part of the debtor exists despite the absence of demand.

Brief explanation will do. Thanks!