What does virtualization allow?

Virtualization allows for the ability to run multiple operating systems on a single machine, which is a significant advantage in both server management and personal computing. This technology creates virtual instances of operating systems that operate independently and concurrently on the same physical hardware.

By doing so, virtualization maximizes resource utilization and reduces hardware costs, as it enables multiple applications or services to run on one machine without the need for separate physical servers for each operating system. This is particularly beneficial in environments where efficiency and scalability are crucial, such as in data centers or when deploying development/test environments.

The other options do not accurately capture the essence of virtualization. For instance, executing only one application at a time contradicts the core capability of virtualization, which is to allow multiple applications or systems to coexist and operate simultaneously. Additionally, while virtualization can enhance resource allocation, it does not physically increase the size of hardware resources; rather, it optimizes the use of existing hardware. Lastly, while virtualization reduces the necessity for some hardware, it cannot entirely eliminate the need for physical components, as those physical resources still underpin the virtualized environments.