What is a key feature of the Global Positioning System (GPS)?

The key feature of the Global Positioning System (GPS) is that it comprises a constellation of a minimum of 24 satellites. This configuration is designed to ensure that at least four satellites are visible from any point on the Earth's surface at any given time. The 24 satellites provide enough coverage and redundancy to deliver accurate positioning data, allowing for reliable navigation and timing services.

While other options suggest different numbers of satellites, the specification of 24 is based on the need for sufficient satellite visibility to enable accurate determination of a user's location using triangulation methods. This setup enables GPS receivers to calculate their position by evaluating signals from multiple satellites, ensuring effective global coverage and operational reliability.