What is the name of the Microsoft IDE used for developing websites, web apps, and mobile apps?

The correct choice identifies Visual Studio as the Microsoft Integrated Development Environment (IDE) designed for developing websites, web applications, and mobile apps. Visual Studio is renowned for its robust set of tools and features, which support a variety of programming languages, including C#, VB.NET, and JavaScript, making it a versatile choice for developers.

Additionally, Visual Studio offers comprehensive debugging, testing, and deployment functionalities that streamline the development process, facilitating both front-end and back-end development for various application types. Its integration with Microsoft platforms and services, such as Azure, further enhances its capabilities in building modern applications.

The other options, while they are popular development tools, are not affiliated with Microsoft; NetBeans is primarily used for Java development, Xcode is Apple's IDE for macOS and iOS applications, and Atom is a hackable text editor by GitHub that lacks the comprehensive features of a full IDE like Visual Studio.