The Army has an urgent requirement for trucks that can operate under arctic conditions. The Contracting Officer on the current contract for trucks tells the contractor to install special snow tires on a shipment of trucks. The Contracting Officer does not have enough time to negotiate the price up front, but she limits the Government's risk by putting a not-to-exceed (NTE) price on the work. This is an example of what kind of modification?
a. A modification that is definitized
b. A supplemental agreement
c. A change order that is undefinitized
d. A constructive change