In RUCKUS ICX devices, interfaces can be configured to support both IPv4 and IPv6 addresses concurrently, a setup known as dual-stack configuration. This allows the interface to handle both IPv4 and IPv6 traffic simultaneously.

Given the configuration:

ICX-Router (config)# ipv6 unicast-routing

ICX-Router (config)# interface ethernet 1/3/1

ICX-Router (config-if-e1000-1/3/1)# ip address 10.172.10.1/24

ICX-Router (config-if-e1000-1/3/1)# ipv6 address 2001:db8:12d:1300::/64

The command ipv6 unicast-routing enables IPv6 routing on the device globally.

Within the interface configuration mode for Ethernet 1/3/1, the ip address command assigns an IPv4 address, and the ipv6 address command assigns an IPv6 address to the same interface.

This configuration allows the interface to transmit and receive both IPv4 and IPv6 traffic simultaneously, facilitating communication in a dual-stack network environment.

Therefore, the correct statement is:

B. The interface will transmit and receive both IPv4 and IPv6 traffic simultaneously.