What do we call a person in possession of an instrument?

The term "Bearer" is the correct answer because it refers to an individual who possesses an instrument, such as a negotiable instrument or a financial document, and can present it for payment or transfer. In the context of financial instruments, being the bearer means that the person has physical possession of the document and is entitled to the rights associated with it, such as receiving payment.

In the context of other options, a "Holder" generally refers to someone who has legal rights to the instrument due to possession but may not have the same immediate claim to payment as a bearer. A "Payee" is the individual named on an instrument who is entitled to receive payment, while an "Endorser" is a person who signs the back of a negotiable instrument to transfer it to someone else. The nuances of these terms highlight that "Bearer" specifically emphasizes possession, which is fundamental in determining who has the right to enforce or claim payment on the instrument.