What condition would explain why the virtual machine is failing to boot in an offsite datacenter running on vSphere 5.5?

A new vApp was built and tested in the corporate headquarters datacenter running vSphere 6.x.

What condition would explain why the virtual machine is failing to boot in an offsite datacenter running on vSphere 5.5?
A . The virtual machine was built with the default hardware version.
B . The VMFS 5 datastore is not compatible with virtual machines configured with vSphere 6.x.
C . A DRS 5.5 cluster cannot run virtual machines configured with vSphere 6.x.
D . The VMDK file is locked.

Answer: A