Assuming hello PDU authentication has been disabled, which command re-enables the feature on a FabricPath interface?

Assuming hello PDU authentication has been disabled, which command re-enables the feature on a FabricPath interface?
A . switch (config-if) # fabricpath isis authentication-type cleartext
B . switch (config-if) # fabricpath isis authentication-type md5
C . switch (config-if) # fabricpath isis authentication check
D . switch (config-if) # fabricpath isis hello-interval

Answer: C