As shown in the figure, the MSR router in the headquarters is connected to the branch through two 100Mbps Ethernet links. To make full use of the existing bandwidth resources, which of the following routing schemes is the best?

A . The two Ethernet links between the headquarters and the branch run the OSPF protocol at the same time to realize ECMP
B. The primary link runs OSPF, and the backup link runs RIP
C. Run RIP on the main link, configure static routing, the outgoing interface points to the backup link, and set the priority value to 150
D. The main link runs OSPF, configures static routing, and the outbound interface points to the backup link

Answer: A