What is the main difference between "synchronous" and "asynchronous" communication tools in a remote work context?

A Synchronous tools require participants to interact in real time, while asynchronous tools allow people to respond at different times B Synchronous tools only work over Wi-Fi, while asynchronous tools only work over cellular data C Synchronous tools are always video-based, while asynchronous tools are always audio-based D There is no real difference; the terms are interchangeable