when is a route in the routing table placed in the "possibly down" state?

With a distance vector routing protocol like RIPv1, when is a route in the routing table placed
in the “possibly down” state?

A.
when a router receives an update from its neighbor router about a network in its routing
table but with a worse metric

B.
when a router receives an update from its neighbor router about a network in its routing
table but with a better metric

C.
when a router receives an update from its neighbor router indicating that a previously
accessible network is now inaccessible

D.
whenever the router receives an update from its neighbor about a newly learned network

E.
whenever the router interface that is used to reach the remote network goes down