Final answer:
Docker is the best choice for providing a portable environment for virtualized applications, due to its containerization technology making it lightweight and highly portable compared to traditional virtualization platforms like VirtualBox, Hyper-V, and VMware.
Step-by-step explanation:
To provide a portable environment for virtualized applications, the most appropriate choice from the list you provided would be Docker. Docker is a platform that uses containerization technology to package an application and its dependencies into a container that can run on any Linux server. This ensures consistent behavior regardless of where the container is deployed, making it a very portable solution.
VirtualBox, Hyper-V, and VMware are more traditionally virtualization platforms where each virtual machine includes not only the application and its dependencies but also an entire operating system. While they do provide portability, they are generally heavier than Docker containers and may require more resources. Hence, for a lightweight and portable solution that is easy to share and deploy, Docker stands out as the best option.