Router-A has an OSPF route to destination 172.18.3.0/24 with four equal-cost paths. How will Router-A forward traffic destined to 172.18.3.5 based on Junos OS’s default behavior?

A.
Traffic will be load-balanced on all four available paths.

B.
Traffic will be forwarded over the one path installed in the forwarding table.

C.
Traffic forwarding will be rotated across each of the four paths for 1 minute on each path.

D.
Traffic forwarding behavior depends on the hardware platform.

Explanation:
Understanding OSPF Traffic Control

Once a topology is shared across the network, OSPF uses the topology to route packets between network nodes. Each path between neighbors is assigned a cost based on the throughput, round-trip time, and reliability of the link. (OSPF assigns a default cost metric of 1 to any link faster than 100Mbps.) The sum of the costs across a particular path between hosts determines the overall cost of the path. Packets are then routed along the shortest path using the shortest path first (SPF) algorithm. If multiple equal-cost paths exist between a source and destination address, OSPF routes packets along each path alternately, in round-robin fashion.

To control the flow of packets across the network, OSPF allows you to manually assign a cost (or metric) to a particular path segment. For example, if all routers in the OSPF network use default metric values, and you increase the metric on one interface to 5, all paths through this interface have a calculated metric higher than the default and are not preferred.
You can also control the flow of packets through the network using route preferences. When several routes have the same SPF calculation, OSPF uses route preferences to select the route that is installed in the forwarding table. To evaluate a route, OSPF calculates the sum of the individual preferences of every router along the path and selects the route with the lowest total preference.

By default, internal OSPF routes have a preference value of 10, and external OSPF routes have a preference value of 150. Suppose all routers in your OSPF network use the default preference values. By setting the internal preference to 7 and the external preference to 130, you can ensure that the path through a particular device is selected for the forwarding table any time multiple equal-cost paths to a destination exist.

Additional information:
http://www.juniper.net/techpubs/software/junos/junos95/swconfig-routing/id-10120848.html