The correct option is 4 (Section 13). Section 13 of the Negotiable Instruments Act, 1881 specifically defines what constitutes a "Negotiable Instrument." It states that a negotiable instrument is a document that is transferable and can be used to claim the payment of a specific amount. This includes instruments such as promissory notes, bills of exchange, and cheques. The section outlines the basic characteristics of negotiable instruments, including their transferability, which is central to their legal function. Other sections, such as Section 4 (defining "instrument") and Section 138 (dealing with dishonor of cheques), do not specifically define negotiable instruments, making Section 13 the correct provision for this purpose.