Final answer:
Airlines now commonly charge a fee for checking luggage, which is part of the broader changes in airline security and operations since 9/11, including long wait times.
Step-by-step explanation:
The student asked which item many airlines now charge a fee to check when flying. The correct answer is A) Luggage. Since the 9/11 hijackings, security procedures have become more stringent, leading to various changes in the airline industry, including fees for checked baggage. These changes also entail more intensive security screenings, resulting in longer wait times at the airport, which is a significant opportunity cost for travelers. The United States Department of Transportation reported that there were 895.5 million systemwide scheduled service passengers in 2015, all of whom had to deal with these extended security measures and potential baggage fees.