Mountain airlines has annual operating revenues of less than $75 million with hubs in denver and salt lake city. this airline would be classified in which air carrier category?

Regional carrier                  

Explanation:

Like in many countries, in United States, the airlines are either privately owned or publicly owned. In the United States, airlines are categorized in to major airline carriers, national airline carriers and regional airline carriers by the revenue it generates.

Accordingly, if an airline generates revenue more than 1 billion dollar in a year, it falls in the Major Airline carriers category.

It the revenue generated by the airline is within the range of $100 million to $1 billion, then it is called National airline carriers.

However, if the revenue is less than 100 million dollar for a year, then that airline is called a Regional airline carrier.

In the context, as the revenue generated by the Mountain Airlines is less than  75 million dollar, it is called Regional carrier.

Hence, the answer is --- Regional carrier