which two important key chain considerations should be accounted for?

When using MD5 route authentication on routers running RIP or EIGRP, which two important key chain considerations should be accounted for? (Choose two.)

A.
The lifetimes of the keys in the chain should overlap.

B.
Key 0 of all key chains must match for all routers in the autonomous system.

C.
Routers should be configured for NTP to synchronize their clocks.

D.
No more than three keys should be configured in any single chain