What describes conditions that may be attached to discount fares?

The correct choice focuses on the specific conditions often associated with discount fares in the travel industry. Discount fares are usually offered at a lower price but come with certain stipulations that travelers must adhere to in order to benefit from the reduced rate.

Advance purchase refers to the requirement that tickets must be bought a certain number of days before the travel date. This encourages travelers to commit to their travel plans in advance. Length of stay indicates the minimum or maximum duration for which the ticket must be valid; for example, some discount fares might require a minimum stay of a weekend or a specific number of nights.

These conditions are put in place to help airlines manage demand and optimize their pricing strategy, ensuring that discounts attract passengers while mitigating the potential loss of revenue from more flexible fare options. Understanding these conditions is crucial for travelers who wish to take advantage of lower rates while being aware of the limitations.