Which technology allows a computer to run multiple operating systems at the same time?

The correct answer is the technology known as a hypervisor, which plays a crucial role in virtualization. A hypervisor is a software layer that sits between the hardware and the operating systems to manage and allocate hardware resources to multiple guest operating systems. It enables the simultaneous execution of different operating systems on a single physical machine by creating virtual machines, each equipped with its own virtual hardware. This capability allows organizations to optimize hardware utilization, run various applications in isolated environments, and streamline development and testing processes.

In contrast, other choices reflect different concepts in computing. Cloud computing refers to the delivery of computing services over the internet, allowing for on-demand resource access but does not specifically address running multiple operating systems concurrently on a single machine. A Virtual Machine Manager is a term that can describe software managing virtual machines but does not specifically denote the core function of virtualization as a hypervisor does. An Operating System Emulator typically replicates the behavior of a specific operating system, enabling applications designed for one OS to run on another, but it does not inherently support the simultaneous execution of multiple operating systems as a hypervisor does.