Which three scenarios are likely causes of this error message?

An administrator has been tasked with enabling High Availability (HA) on a cluster in a vSphere 6.x environment with default settings. The cluster configures properly and there are no errors.

The next day when powering on a virtual machine, an error is presented:

Not Enough Failover Resources

Which three scenarios are likely causes of this error message? (Choose three.)
A . The default VM Monitoring Sensitivity is set too high.
B . There are not enough datastore heartbeat datastores configured by default.
C . The default slot size in the cluster is set too high.
D . There are virtual machines with large CPU reservations.
E . A host is in maintenance mode for a replacement of a failed Hard Drive.

Answer: C,D,E