43. Should the federal district court in State A grant the banker's motion to transfer?

A is correct. The court should deny the banker's motion to transfer because State A is where a substantial part of the claim arose and is thus a proper venue. In this scenario, the court's decision to transfer to another proper venue is discretionary based on the convenience of the parties and witnesses and the interest of justice. Here, State A law would apply. A court sitting in State A would be more familiar with State A substantive law and most of the evidence is present in State A.

B is incorrect. The court should deny the venue transfer, not because State B would be an improper venue. State B would not be an improper venue because the banker, the sole defendant, resides there. However, the court still should deny the motion for the reasons stated above.

C is incorrect. Although it is true that State B would be a proper venue given that the defendant resides there, the claim was originally and properly filed in State A, where it should remain.

D is incorrect. Again, although State B would be a proper venue, the case was filed in State A, so State A's choice-of-law and substantive law governs. It does not matter that, had the action been filed in State B, the federal court in State B would have applied State B law to govern the claim. Upon transfer from the State A federal court, the State B court would still have to apply the state law chosen by State A choice of law rules, so that transfer does not become a tool for forum shopping.