John Agrees to Sell His Sports Equipment Store to Kay

John agrees to sell his sports equipment store to Kay and,as part of the sale,promises not to open a similar store in the United States for twenty years.John's promise is

A) an unreasonable restraint of trade like all covenants not to compete.
B) unreasonable in terms of geographic area and time.
C) unreasonable in terms of Kay's "goodwill" and "reputation."
D) valid and enforceable.