Which of the Following BEST Describes a Single, or Straight

Which of the following BEST describes a single, or straight, ladder?

A) Base section with one or more fly sections, can be adjusted to specific length needed
B) Designed to be used as a self-supporting stepladder, equipped with positive locking devices
C) One section, fixed length, used for quick access to roofs and windows of one- and two-story buildings
D) Telescoping ladder made up of bed rails and hand rails separated by bracing, typically pivoted into place