In the vSphere environment there is a mix of ESXi hosts with versions 5.5, 6.0, and
6.5 in one DRS cluster. What is the highest virtual machine compatibility that can be used on all the hosts?
A. vmx-10
B. vmx-9
C. vmx-11
D. vmx-13
Reference: https://kb.vmware.com/s/article/1003746