Quality of Service (QoS) is the correct answer because it allows network administrators to classify traffic types and prioritize them accordingly, ensuring that business-critical applications receive the necessary bandwidth and low latency they require. Access Control Lists (ACLs) control traffic but do not prioritize it; they are more focused on permitting or denying traffic. VLAN assignment is a Layer 2 operation and is primarily used for segmenting a network into different broadcast domains for security and management purposes. Route summarization simplifies routing but does not deal with traffic prioritization.