A Bangor ladder is described as:

A Bangor ladder is characterized by its design, which includes the use of staypoles. Staypoles are additional supports that extend from the ladder to the ground, providing stability and preventing the ladder from tipping over when in use. This design is particularly useful when the ladder is extended and being used in various positions, enhancing safety for the firefighter.

The other descriptions do not accurately define a Bangor ladder. For example, while some ladders may be single-section and of a certain length, that does not specifically denote a Bangor ladder. Similarly, single beams and the term Pompier ladder refer to different types or styles of ladders that do not encompass the key features of a Bangor ladder. Therefore, the aspect of being equipped with staypoles is what clearly identifies the ladder in question.