The correct answer is 'RAM'. When more virtual machines (VMs) are deployed on a host, there is a greater need for memory to allocate to each VM so they can operate effectively. CPU cores might also seem like a correct choice, but the CPU requirement is more closely related to the processing power needed by the VMs’ workloads rather than the sheer number of VMs. Network bandwidth is associated with data transfer rates and the amount of traffic that can be handled, not directly with the number of VMs. Storage capacity does increase with more VMs, but it is more aligned with the data the VMs hold rather than their operation.