The term, "realization," in revenue recognition refers to which of the following? a. The entity has completed, or substantially completed, the activities it must perform to be entitled to the revenue benefits. b. The product or service has been exchanged for cash, claims to cash, or an asset that is readily convertible to a known amount of cash or claims to cash. c. The entity has received an irrevocable order for goods or services. d. Cash has been received with an irrevocable order for goods or services. e. None of these