Al makes a written job offer to Bea.Al changes his mind and faxes to Bea his revocation, which is received by Bea before she sends her acceptance by mail.

What rule of contract formation controls the outcome of this fact pattern?

1) B's acceptance is valid when received by A.

2) B's acceptance is valid when she sent it to A.

3) A's revocation is valid when sent to B.

4) A's revocation is valid when received by B.