Which of the following is a type of pedestrian crossing device?

The choice highlighting the push-button for pedestrian signals is a common type of pedestrian crossing device that enhances safety and accessibility. This device allows pedestrians to request a pedestrian signal when they wish to cross an intersection, supporting better traffic flow and safer crossing experiences. When a pedestrian presses the button, it activates a sequence in the traffic control system that prioritizes the pedestrian's need to cross, often leading to the signal changing in their favor.

The other options, while relevant to traffic management and pedestrian safety, serve different functions. Flashing stop signs are intended to enhance visibility and alert drivers at intersections but do not specifically assist pedestrians. Voice announcement systems provide audio cues for visually impaired pedestrians, which is vital but not a physical crossing device in the conventional sense. Traffic light countdown timers also serve a purpose in providing information to drivers and pedestrians about the time remaining until the light changes; however, they do not actively create a crossing opportunity as the push-button does. This makes the push-button a critical tool in fostering pedestrian safety and control at crosswalks.