Final answer:
Option (C), OSPF uses cost as its metric, which is calculated based on the bandwidth of the links. Higher bandwidth results in lower cost, making that route more preferred.
Step-by-step explanation:
The metric used by OSPF (Open Shortest Path First) is cost. OSPF calculates the cost of a route based on the bandwidth of the links. A higher bandwidth indicates a lower cost, which makes a route more preferred. The cost value is inversely proportional to the bandwidth of the link, with the formula being cost = reference bandwidth / interface bandwidth. The default reference bandwidth is 100 Mbps. However, OSPF does not directly use delay, reliability, load, or other metrics like some other routing protocols do.