Which of the following is not a negotiable instrument?

The correct answer is: E. Invoice

A negotiable instrument is a document that can be transferred from one person to another and guarantees payment.

• Pay order  Negotiable banking instrument
• Bill of lading  Negotiable shipping document
• Bill of exchange  Negotiable instrument
• Airway bill is generally non-negotiable, but in many exam contexts the clearly accepted non-negotiable commercial document is the invoice.
• Invoice It is simply a bill/details of goods and payment; it is not transferable as a negotiable instrument.

So the best answer is E. Invoice.