Read the following excerpt from a US court opinion:
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(“[W]e conclude that § 1404(a) is the proper avenue of relief where a party seeks the transfer of a case to enforce a forum-selection clause, while Rule 12(b)(3) is the proper avenue for a party’s request for dismissal based on a forum-selection clause.”); Hillis v. Heineman, 626 F.3d 1014, 1016 (9th Cir.2010) (finding that a party’s defense for improper venue under Rule 12(b)(3) based on a forum-selection clause was valid and was not waived by the filing of a counterclaim); Muzumdar v. Wellness Int’l Network, Ltd., 438 F.3d 759, 760-62 (7th Cir.2006) (“A challenge to venue based upon a forum selection clause can appropriately be brought as a motion to dismiss the complaint under [Rule] 12(b)(3).”); Sucampo Pharm., Inc. v. Astellas Pharma, Inc., 471 F.3d 544, 548-50 (4th Cir.2006) ; Riley v. Kingsley Underwriting Agencies,
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What is the most suitable continuation to the opinion? Your options are:
A. recognizing circuit agreement that a motion to dismiss based on an arbitration clause is proper under rule 12b3
B. holding prejudgment denial of motion to dismiss on basis of forumselection clause not to be immediately appealable under  1291
C. holding that since the fifth circuit has accepted rule 12b3 as a proper method for seeking dismissal for improper venue based on a forum selection clause the court need not decide whether a rule 12b1 motion  is appropriate
D. holding that motions to dismiss based on forumselection clause should be analyzed under rule 12b3
E. holding that a forumselection clause may be enforced under rule 12b3 as a motion to dismiss on the basis of improper venue
Reply with [A, B, C, D, E] only.