Final answer:
An invoice is a document requesting payment for products or services provided, making it an example of a bill. A money market account falls into the M2 category of money supply. The degree of imperfect information in purchases is higher when product quality and history are uncertain.
Step-by-step explanation:
The student has asked which of the following is an example of a bill: a purchase order, an invoice, accounts receivable, or an insurance expense. Among the given options, an invoice is the correct answer. An invoice is a document issued by a seller to a buyer that specifies the number of products or services provided and the amount due for payment. This contrasts with a purchase order, which is a document from the buyer to the seller, and accounts receivable, which is money owed to a company. Insurance expense, on the other hand, is the cost of an insurance policy and not a document requesting payment.
Regarding the money market account, it belongs in M2, which includes all of M1 (cash, checking accounts, and traveler's checks) along with savings deposits, money market accounts, and other near monies.
When it comes to making purchases, the degree of imperfect information varies. It tends to be higher when buying products like a used laptop from a garage sale, as there is less certainty about the product's history and condition.