What is the source of the problem?

A vSphere Administrator notices that the newly deployed ESXi hosts cannot stay in a connected state in vCenter Server for more than 60 seconds at a time. The Administrator knows that the hardware is in good health and that the ESXi hypervisors are properly configured.

What is the source of the problem?
A . The hosts are not a part of a vSphere Distributed Switch.
B . Firewall rules that have too many ports open.
C . Firewall rules preventing hosts from sending heartbeats to vCenter Server.
D . The hosts do not have persistent logging configured.

Answer: C