Virtualization technologies enable the creation of virtual machines (VMs) by abstracting hardware resources. Open-source technologies are freely available with accessible source code. Let's evaluate each option:
A . Hyper-V: Hyper-V is a hypervisor developed by Microsoft, integrated into Windows Server and available as a standalone product. It is proprietary, not open-source, as its source code is not publicly available. Not Open-Source.
B . Xen: Xen is an open-source hypervisor maintained by the Xen Project under the Linux Foundation. It supports multiple guest operating systems and is widely used in cloud environments (e.g., Citrix XenServer builds on it). Its source code is freely available. Open-Source.
C . FusionSphere: FusionSphere is Huawei's proprietary virtualization and cloud computing platform, based on OpenStack and other components. While it integrates open-source elements (e.g., KVM), FusionSphere itself is a commercial product, not fully open-source. Not Open-Source.
D . KVM (Kernel-based Virtual Machine): KVM is an open-source virtualization technology integrated into the Linux kernel. It turns Linux into a Type-1 hypervisor, and its source code is available under the GNU General Public License. It's widely used in Huawei's virtualization solutions. Open-Source.
Thus, B (Xen) and D (KVM) are open-source virtualization technologies.