$4..$ Nat signed a two$-$year contract to play soccer for the Scores, for $$100,000$ per game. During the second year of his contract, and just before a big game, Nat demanded that the team owner pay him an additional $$5000$ per game on his contract, starting with the current game. The owner reluctantly agreed to the new contract terms because Nat was the team$$s leading scorer. At the end of the season, Nat demanded the additional $$5000$ per game; the owner refused to pay. What best describes the new contract between Nat and the owner?

A$.$ It is unenforceable because the owner agreed to Nat$$s contract terms under economic duress.

B$.$ It is unenforceable because both parties did not give new legal consideration for the new contract.

C$.$ It is enforceable because both parties gave legal consideration for the new contract.

D$.$ It is enforceable because under the common law, all contract modifications are valid if the parties consent.