please answer ASAP

An offer was sent to an equipment supplier in the mail, which was received by the supplier on March 30. The supplier sent a letter back through the mail communicating acceptance of the offer on April 10. The offeror received the letter on April 17. In light of these facts, and assuming all elements of an enforceable contract are present, when was the contract formed? Select one: a. A contract was never formed. b. April 10. c. March 30. d. April 17