With no explanation, chose the best option from "A", "B", "C" or "D". 997 F.2d 335, 338 (7th Cir.1993) (a presumption exists that a mailing is received where there is "proof of procedures followed in the regular course of operations which give rise to a strong inference that the [correspondence] was properly addressed and mailed”). In any event, on appeal Boomer does not claim that the CSA did not constitute an offer because he did not receive the CSA mailing. 6 . While Boomer challenges the validity of the CSA’s provision concerning the right to attorney’s fees and the clause prohibiting the use of a class action, because we conclude that arbitration is required, these other challenges must be decided by the arbitrator in the first instance. Metro East, 294 F.3d at 929. See also Larry’s United Super, Inc. v. Werries, 253 F.3d 1083, 1086 (8th Cir.2001) (<HOLDING>). Of course in considering Boomer's other

A: holding that once the party seeking to compel arbitration establishes the existence of an arbitration agreement and that the claims raised fall within the scope of that agreement the trial court must compel arbitration
B: holding an appeal may be taken from an order denying a motion to compel arbitration
C: recognizing that in reviewing ruling on motion to compel arbitration we first determine whether party seeking arbitration established existence of arbitration agreement
D: holding that on appeal from an order denying a motion to compel arbitration a court may only determine whether a dispute is subject to arbitration other contractual challenges must be determined by the arbitrator
D.