What does the term "cordon" refer to?

The term "cordon" specifically refers to an extended line of men, vehicles, or fortifications that is set up to prevent access or egress to a certain area. This definition aligns with the concept of establishing a perimeter to control movement in and out of a designated space, often seen in military or law enforcement contexts. A cordon is typically used to secure an area, either for safety reasons or to contain a situation, effectively blocking passage through an outlined boundary.

In contrast, while options discussing restricted access, security measures, and protection may relate to the function of a cordon, they do not accurately capture the specific meaning and usage of the term. The precise concept of an extended line or barrier is what distinguishes the correct answer from the more general interpretations of the others.