Which of the following represents an open-source mobile operating system?

Google Android represents an open-source mobile operating system because it is based on the Linux kernel and is developed under the Apache License, which allows developers to view, modify, and distribute the source code. This openness fosters collaboration and innovation within the developer community, enabling a wide range of applications and customizations for various devices.

In contrast, Apple iOS is a proprietary operating system, meaning that its source code is not publicly available and is tightly controlled by Apple. Windows and macOS also fall into the category of proprietary operating systems, with their source code being restricted and not open for public modification. This distinction highlights the significance of Android's open-source nature, allowing for greater flexibility and a broader ecosystem of applications and devices tailored to user needs.