Final answer:
Purchase orders are sent by buyers to vendors, indicating the business transaction details. They are crucial in business operations and supply chain management.
Step-by-step explanation:
Purchase orders are formal documents sent by buyers to sellers, specifying the type, quantity, and agreed prices for products or services. The correct answer to the question 'Purchase orders are sent to:' is b. vendors. Vendors or suppliers receive purchase orders so they can fulfill the sale and deliver the requested goods or services to the purchasing entity, ensuring that both parties are clear about the transaction's details. This process is a fundamental aspect of business operations and supply chain management.