(a) An arbitration agreement must be in writing. The agreement is in writing if it is contained in:
(1) a document signed by each party;
(2) an exchange of letters, telexes, telegrams, or other means of telecommunication that provide a record of the agreement; or
(3) an exchange of statements of claim and defense in which the existence of an agreement is alleged by one party and not denied by another.
(b) A contract reference to a document containing an arbitration clause is an arbitration agreement if the contract is in writing and the reference is sufficient to make that clause part of the contract.