An oral agreement is entered into between two Heads of State. It provides that State X will pay State Y $1,000,000.00 per year; in return State Y must deliver 100 Widgets to State X each year. This agreement is:

A) invalid, absent subsequent ratification by the appropriate bodies within each State.

B) inalid, because it is only oral.

C) valid as it is.

D) valid, as long as there is an implied agreement that it will be promptly put into writing.