Castillo offered to sell a pawn shop to Trudy. Castillo mailed the offer to Trudy by first-class U.S. mail. The offer did not specify the required manner of acceptance.

a. Under modern rules, how can Trudy communicate an acceptance of the offer to Castillo?

b. When will Castillos offer lapse if he did not specify a cancellation date in the offer?

c. If Trudy sends an acceptance by first-class U.S. mail, when will the acceptance be effective?