Which statement is true about the Cisco ASA interface monitoring?

A.
ASA does not clear the received packets count on the monitored interface before
running the tests.

B.
Interfaces of the same context cannot be monitored.

C.
It is possible to configure a context to monitor a shared interface.

D.
If the monitored interface has both IPv4 and IPv6 addresses then it cannot be
monitored.

Explanation:
You can monitor up to 250 interfaces (in multiple mode, divided between all contexts).
You should monitor important interfaces. For example in multiple mode, you might
configure one context to monitor a shared interface. (Because the interface is shared, all
contexts benefit from the monitoring.)

http://www.cisco.com/c/en/us/td/docs/security/asa/asa91/configuration/general/asa_
91_general_config/ha_failover.html