Supplies and prepaid expenses are described as never becoming which of these?

1. A source of funds has to be able to turn into money. 2. Inventory can, though slowly, because it can be sold. 3. Supplies and prepaid expenses never become cash. 4. So they are not a source of funds to pay bills. _Source: OpenStax Principles of Finance (CC BY 4.0), Ch 19 'The Importance of Trade Credit and Working Capital in Planning', sections 19.1-19.5_