Final answer:
The advice to marchers to not carry nail files is similar to post-9/11 air travel rules that restrict sharp objects for safety. Both sets of precautions are meant to maintain security and prevent potential harm in their respective contexts.
Step-by-step explanation:
The advice to keep nail files out of their pockets given to the march leaders can be compared to modern air travel regulations post-September 11, 2001. After the 9/11 attacks, stringent rules were implemented concerning what passengers could carry on flights. There are prohibitions against carrying certain items such as sharp objects, and passengers are subjected to thorough screening processes to ensure the safety of air travel.
Just as the march leaders were advised to avoid carrying potential weapons like nail files for the safety and success of their civil rights demonstrations, modern travelers are advised to travel without sharp items for the collective security of the passengers and crew. This comparison highlights the evolution of safety regulations in different contexts of societal concern – from maintaining the peacefulness of a protest march to ensuring national security in the skies.