Which statement describes an EIGRP feasible successor route?

Which statement describes an EIGRP feasible successor route?
A . A primary route, added to the routing table
B . A backup route, added to the routing table
C . A primary route, added to the topology table
D . A backup route, added to the topology table

Answer: D

Explanation:

Two terms that appear often in the EIGRP world are "successor" and "feasible successor". A successor is the route with the best metric to reach a destination. That route is stored in the routing table. A feasible successor is a backup path to reach that same destination that can be used immediately if the successor route fails. These backup routes are stored in the topology table.

Reference: http://study-ccna.com/eigrp-overview