With no explanation, chose the best option from "A", "B", "C" or "D". prong The gravamen of each of Plaintiffs’ complaints, no matter how legally characterized, is that defendants intentionally breached a duty of “best execution.” We have not yet addressed whether breach of the duty of best execution violates federal securities law. But, four of our sister circuits have held that breach of that duty can violate § 10(b) and Rule 10b-5 under certain' circumstances. See Kurz v. Fid. Mgmt. & Research Co., 556 F.3d 639, 640 (7th Cir. 2009) (“Best execution ... affects the net price that investors pay or receive for securities and is accordingly widely understood as a subject of regulation under the Securities and Exchange Act of 1934 ....”) (internal'quotation marks and citation omitted); Gurfein v. Ameritrade, Inc., 312 Fed.Appx. 410, 412 (2d Cir. 2009) (<HOLDING>); Geman v. SEC, 334 F.3d 1183, 1187-88, 1192-93

A: recognizing defense in securities case
B: holding that a state securities claim which alleged federal mail wire and securities violations as the predicate acts did not arise under federal law and thus did not create federal jurisdiction
C: recognizing a duty of best execution under federal securities law
D: holding breach of best execution duty is a material misrepresentation in connection with the purchase or sale of the securities
C.