Final answer:
Credit open provides the greatest risk for the seller, while cash in advance provides the least risk.
Step-by-step explanation:
The mode of payment that provides the greatest risk for the seller is credit open. In a credit open transaction, the seller ships the goods to the buyer without receiving any payment upfront. The buyer promises to pay the seller at a later date, usually within a specified period of time. This exposes the seller to the risk of non-payment or late payment by the buyer.
On the other hand, cash in advance is the mode of payment that provides the least risk for the seller. In this payment method, the buyer pays the seller in full before receiving the goods or services. The seller is guaranteed full payment and eliminates the risk of non-payment.
Documentary and account collections are payment methods that provide some level of risk for the seller, but the risk is lower compared to credit open. In documentary payment, the seller ships the goods after receiving certain documents that prove payment obligations. In account collections, the seller ships the goods and then collects payment from the buyer at a later date.