Final answer:
Personal checks carry the highest risk for sellers due to potential insufficient funds, stop payment orders, and fraud. Credit card payments are secured by the company, and bank transfers are immediate and irreversible, presenting lower risks.
Step-by-step explanation:
Among the options given, personal checks present the greatest risk for the seller since they are subject to a variety of issues including insufficient funds, stop payment orders, and potential fraud. A credit card transaction, on the other hand, has the security of the credit card company backing the payment, almost guaranteeing that the seller will receive the funds. A bank transfer is usually immediate and irreversible, ensuring the seller receives the money directly from the buyer's account.
Cash on delivery (COD) is generally safe, but it does require the physical exchange of cash upon delivery, which may pose logistical challenges or risks of theft. This delay and the potential for non-payment make personal checks the riskiest mode of payment for sellers.