Detailed Instructions: In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".
Q: [header] How to arrange for your child to travel internationally as an unaccompanied minor [title] Check each airline's restrictions. [step] While there are general minimum restrictions that apply for all airlines, most have their own requirements for unaccompanied minors on international flights. Ages and documentation may differ depending on the airline and the destination country. <sep> (A) Contact a flight attendant and discuss your concerns with them. [substeps] Some airlines allow students or students to visit the same airline twice a year. (B) [substeps] In particular, some airlines won't accept unaccompanied minors as passengers on international flights at all. Other airlines allow unaccompanied minors on international flights, but won't take children under a certain age, such as 10 or 12. (C) Flight duration may depend upon the website for those airline websites. They are most commonly specified in the airline's charter guide window. (D) [substeps] The exception to this may be if you are traveling nationally. This is because the airline may only allow children to travel by car or public transport.
A:
B