Elastic load balancing distributes incoming application traffic dynamically across multiple backend instances based on current load and capacity, while continuously performing health checks against each instance to detect when one becomes unhealthy or unresponsive, automatically routing traffic away from failing instances toward healthy ones. This combination of dynamic traffic distribution and automated health-based instance detection is exactly the pair of capabilities the scenario requires, making elastic load balancing the correct and purpose-built solution. Link aggregation (A) combines multiple physical network links into a single logical connection to increase bandwidth and provide link-level redundancy, but it operates at the network interface layer and has no concept of application-level instance health or traffic distribution across VM instances. Multipathing software (B) manages redundant I/O paths between a host and storage devices, ensuring storage connectivity survives a path failure; it is unrelated to distributing application traffic across compute instances. NIC teaming (D) similarly addresses network interface redundancy on an individual server, improving that server's own network resiliency, but does not distribute traffic across multiple VM instances or monitor their application-level health. Elastic load balancing correctly and comprehensively satisfies the scenario.

Reference topic: Fault Tolerance Techniques - Elastic Load Balancing and Health Checks.