Final answer:
The alternative to the Trucker's Policy for regular public transportation services is the Passenger Transportation Policy (B). In the case of Greyhound and Trailways, the narrower definition of "market for intercity bus service" would have likely been preferred to avoid antitrust concerns by not including other modes of transportation in the market share analysis.
Step-by-step explanation:
For companies that offer transportation services to the public on a regular basis and not for hire, the policy used as an alternative to the Trucker's Policy is the B) Passenger Transportation Policy. This type of policy is designed specifically for businesses that provide scheduled transportation services to passengers, which differs from commercial or for-hire transportation policies that cover businesses transporting goods or providing non-scheduled passenger services.
In relation to the historical example of Greyhound Lines, Inc. and Trailways Transportation System, the preferred market definition for these companies would likely be "the market for intercity bus service". This narrower definition would help them argue that their merger would not create a monopoly or significantly reduce competition, as it would not include other forms of transportation such as personal cars, car rentals, trains, or flights in the analysis of market share.