3: Explains how a developer could test a website for cross-platform compatibility. 2: Outlines how, OR identifies strategies. 1: Some relevant information.

A web developer can use browser developer tools. These tools, built into most modern browsers, allow developers to simulate how their website looks and behaves on different devices and screen sizes. By using these tools, developers can identify and fix any issues related to cross-platform compatibility, ensuring that the website works well across a variety of devices and browsers.