How many GPS satellites are typically in operation at any given time?

The correct answer reflects the typical operational constellation of Global Positioning System (GPS) satellites, which is designed to ensure adequate coverage and service to users globally. The GPS network is comprised of at least 24 satellites, which are distributed across multiple orbital planes to provide coverage even in challenging geographic environments.

Having around 24 satellites in orbit allows for multiple satellites to be visible from any point on Earth, which is essential for accurately determining a user's position through triangulation. Each satellite broadcasts signals that include its location and the precise time the signals were transmitted, enabling GPS receivers to calculate their distance from the satellites. The need for redundancy means there are often more than 24 satellites in orbit, since some may be undergoing maintenance or repairs, but the minimum operational requirement is 24.

The other options represent numbers that are either too few to ensure global coverage or are more than the operationally required satellites for effective navigation. A system with only 12 satellites would be insufficient for reliable positioning due to limited visibility, while 30 exceeds the necessary amount needed for coverage, resulting in an inefficient use of resources.