问题：

[单选] Multicast is being deployed in the network， and only ip pim sparse-dense mode has been configured on all interfaces in the network to support a new video streaming application. No other multicast configuration was applied anywhere in the network. Since enabling multicast， the network monitoring tools show periodic spikes in link utilization throughout the network， even in areas where the video application is not being used. What could be a possible cause？（）

A . PIM sparse mode is being used.
B . PIM dense mode is being used.
C . The BGP multicast address family has not been configured.
D . IGMP version 3 is being used.
E . IP PIM neighbor filters have not been applied.