The software agent management plane must support auto-scaling and elasticity because traditional security tools are not designed for the speed and scale of cloud environments. Managing Cloud guidance explains that cloud workloads can be created, scaled, and terminated rapidly, often within minutes or seconds.

If security management systems cannot scale at the same pace, workloads may operate without protection or monitoring. Elastic security management ensures that agents are deployed, configured, and decommissioned automatically as workloads scale up or down.

The other options do not directly explain the need for elasticity. Network isolation, reduced services, and firewall port usage are not the primary drivers. Therefore, the need to match cloud velocity makes option C correct.