Regarding the Cisco IPS NME, when should the heartbeat reset be disabled on the ISR?

A.
when performing an upgrade on the ISR

B.
when the NME is used in inline mode

C.
when the NME is used in promiscuous mode

D.
when the NME is used in fail-open mode

E.
when the NME is used in fail-closed open mode

F.
when performing an upgrade on the NME

Explanation:
http://www.cisco.com/en/US/docs/security/ips/7.0/configuration/guide/cli/cli_system_images.ht ml