Veggie Bowl Café Signs an Instrument in Favor of Whole

Multiple Choice

Veggie Bowl Café signs an instrument in favor of Whole Wheat Company that states it is "subject to a certain agreement between buyer and seller." This instrument is

A) negotiable.
B) nonnegotiable, because it is made subject to a separate agreement.
C) nonnegotiable, because it refers to a separate agreement.
D) nonnegotiable, because the buyer and seller are not the same parties.