Which of the following is part of the payment terms according to the invoice requirements?

The payment terms specified in the contract must be included on the invoice because this practice ensures clarity and alignment between what has been agreed upon and what is being invoiced. Including these terms on the invoice helps to prevent disputes regarding payment expectations and reinforces the contractual obligations. This approach promotes transparency for both the contractor and the client, ensuring that all parties are aware of when payments are due and what conditions apply to those payments.

In contrast, the other options present scenarios that do not align with standard practices for payment terms. For example, having a payment due date coincide with the project's start date might not reflect the completion of work or deliverables, which could lead to confusion about when payment is actually required. Making all payments in cash limits flexibility for clients and does not accommodate various payment methods that may be more convenient. Lastly, requiring payments only upon customer request could lead to inconsistent payment practices and delayed cash flow, which is generally not advisable in a contractual agreement. Thus, the correct answer reinforces the importance of adhering to established contractual obligations by ensuring that they are clearly stated in invoices.