Shelby Offers to Make Digital Copies of Relay Company's Business

Shelby offers to make digital copies of Relay Company's business conference videotapes,CDs,DVDs,and other media for $500.Under the mailbox rule and the Uniform Electronic Transactions Act (UETA) ,Relay's acceptance by e-mail will be considered effective when

A) received.
B) sent.
C) followed up by a confirmation letter sent by regular mail.
D) composed on a Relay computer.