Final answer:
The non-monetary item listed is the customer list. It is an intangible asset without a fixed monetary value, unlike accounts payable, foreign exchange gain/loss, and sales that involve monetary transactions.
Step-by-step explanation:
The non-monetary item among the options provided is b) Customer list.
Non-monetary items are items that are not represented in money and do not have a fixed or determinable money value. Examples include intangible assets, inventories, property, plant, and equipment.
In contrast, accounts payable (option a) and foreign exchange gain/loss (option c) are monetary items because they represent amounts that are to be received or paid in money. Sales (option d) are also not a non-monetary item as sales transactions involve monetary exchange.