Fidelity Corporation offers to hire Ron to replace Monica, who has given Fidelity a month's notice to quit. Fidelity gives Ron a week to decide whether to accept. Two days later, Monica signs an employment contract with Fidelity for another year. The next day, Monica tells Ron of the new contract. Ron immediately sends a letter of acceptance to Fidelity. Do Fidelity and Ron have a contract? Why or why not?