Which action enables an IPv6 multicast router on a subnet with locally attached receivers to quickly determine if there is a need to send traffic for a certain multicast group out to that subnet? 

Answer options:

A. Adjust the MLD report interval on the router.
B. Activate IGPMv3 snooping and fast-leave.
C. Enable the MLDv2 explicit-tracking feature.
D. Decrease the ICMPv4 multicast query timer.

B