Final answer:
Option (a), McMillon's company plans to concentrate its gun business on hunting rifles and ammunition, reflecting past utilizations and regulations of firearms aligned with militia activities.
Step-by-step explanation:
According to McMillon, the company would focus its gun business entirely on hunting rifles and ammunition. This decision echoes historical precedents where firearms have played a significant role in the militia and national defense, as seen with the widespread adoption of the .30-06 cartridge among hunters and sportsmen post-World War I.
It is notable, in the case of United States v. Miller, that the regulation of firearms by the federal government and states is permissible when the weapons do not maintain a reasonable relationship to the well-regulated militia, which further supports the focus on hunting rifles and ammunition that are commonly used by civilians.