For testing responsive web design, JavaScript relies on _________ to simulate different screen sizes.

JavaScript relies on Media Queries to simulate different screen sizes for testing responsive web design. Media Queries are a CSS technique that allows developers to apply different styles to a document based on various factors, such as screen size, resolution, and device characteristics. In the context of responsive web design testing, Media Queries help simulate how a web page will appear on devices with different screen sizes, ensuring a consistent and user-friendly experience across a variety of devices.