Which one of the following options for the Check credit limit field will check the customer's credit limit against the customer balance and deliveries?

The option that enables checking the customer's credit limit against both the customer balance and deliveries is the one that combines the balance with packing slip or product receipt. This is significant because it ensures that not only the current outstanding customer balance is taken into account, but also any pending transactions represented by packing slips or product receipts. By doing so, it provides a more comprehensive view of the customer’s financial status and obligations, helping to prevent any potential credit issues before fulfilling additional orders.

In contrast, the other options do not combine the necessary elements for a full assessment of the credit risk. For instance, simply using the balance does not account for pending deliveries that might affect the customer’s available credit. Similarly, options like "Balance + All" or "Balance + sales agreement" may not specifically incorporate all relevant transactional aspects like those found in packing slips or product receipts, which are key in assessing immediate credit risk associated with current and upcoming orders.