What is the main advantage of using virtual machines?

Virtual machines provide the significant advantage of allowing multiple operating systems to run simultaneously on a single physical machine. This capability is enabled by virtualization technology, which abstracts the physical hardware and allows various operating systems to coexist in isolated environments, referred to as virtual environments or instances. Each virtual machine operates as if it were a separate physical computer, enabling users to test applications across different OS platforms, run applications that are specific to certain operating systems, or develop and test software in a safe environment without the need for multiple physical devices.

The other choices do not capture the primary advantage as effectively. While virtual machines can contribute to reducing hardware costs indirectly by maximizing resource utilization, this is not their defining characteristic. Interestingly, they do not inherently increase internet connection speeds or guarantee greater security compared to traditional computers; these factors depend more on the implementation, configuration, and specific use cases rather than the virtualization itself.