Choice "C" is correct. Transaction cycles generally capture commonly occuring transactions (e.g., customer orders) and process them repeatedly in a nearly identical fashion. Transaction cycles are established to organize and process data in an efficient manner.
Choice "d" is incorrect. Transaction cycles group transactions because they are similar in nature and have similar processing requirements. For example, most sales are processed in the same way for a particular business.
Choice "b" is incorrect. Transaction cycles are typically identified as a means of promoting processing efficiency. Transactions are processed in nearly identical ways.
Choice "a" is incorrect. Custom transactions may be identified within revenue cycles, however, they would be processed individually and specifically (e.g., establishing capital accounts for owners and borrowing funds for capital expansion would be handled individually).