Monk and Jenkins leased a building they owned to Tuneup Masters for five years. The lease contained a provision to extend the lease an additional five years by sending a certified or registered letter at least six months prior to the expiration of the lease. Within that five- year period, the vice president of Tuneup Masters exercised the renewal option by delivering a letter to the U. S. Postal Service and having it certified. This letter to the landlords was lost in the mail. Not having received the letter, the landlords refused to renew the lease. Tuneup Masters claimed that the renewal was valid even though the certified letter was lost. Is Tuneup correct?