how many point-to-point communication links does the slave has with the master host?

In a HA cluster how many point-to-point communication links does the slave has with the master host?

A.
3

B.
4

C.
2

D.
1

Explanation:
http://www.slideshare.net/esloof/introduction-vsphere-5-high-availability-ha

Each slave maintains a single TCP connection to the master