[Solved] The term observable universe refers to . A)the portion of the universe that can be seen by the naked eye B)the portion of the universe that is not hidden from view by, for example, being below the horizon C)that portion of the universe that we can see in principle, given the current age of the universe D)that portion of the universe that we have so far photographed through telescopes Single-Entry Bookkeeping System: An accounting method in which each financial transaction is recorded only once in account books; similar to a checkbook register; the journal for each transaction is recorded in one column, or on a single line, to account for either a positive or negative amount to demonstrate the receipt or disbursement of cash. Checkbook Register: A record of all deposits, withdrawals, checks, and transactions made through a checking account. Cash Control Sheet: A financial document used to track the inflow and outflow of cash within a business to ensure accurate accounting and prevent fraud. Pegboard System: An organizational tool consisting of a board with holes that can hold pegs or hooks for the purpose of hanging or displaying items.