Final answer:
Antivirus software should be installed on both the host computer and each of the virtual machines in a virtualization environment to ensure complete protection against viruses and malware.
Step-by-step explanation:
The question pertains to the correct placement of antivirus software within a virtualization environment. It's important to understand that virtual machines (VMs) behave like separate computers and can be affected by viruses and malware independently of the host system. Therefore, for thorough protection, antivirus software should be installed on both the host computer and each of the virtual machines. This ensures that the host is protected from threats that could cross from a compromised virtual machine, and each individual VM is protected from threats that could enter through their own network connections or shared folders.