Which assumption is made about materials when a department is tracked under process costing?

1. Two assumptions govern the departmental calculations. 2. The first is that all materials needed for a batch in a department are added when the batch is started. 3. The second is that a batch started in a department is completed either that month or the following month. 4. The materials assumption is what makes equivalent units for materials either zero or the full whole unit count. 5. If materials were added evenly, partly finished units would carry only a fraction of materials cost, which is not how these grids are built. _Source: Jonick, Principles of Managerial Accounting (UNG Press, CC BY-SA 4.0), section 3.2 Process Costing Transactions for a Manufacturing Company_