The three major benefits of SLM with EAS are: 'Can incorporate Business Advocate as an additional feature', 'Less average delay to answer', and 'Greater control over providing differentiated service'. Incorporating Business Advocate enhances the system's functionality (A), reducing the average delay to answer improves efficiency (B), and having greater control over providing differentiated service is crucial for tailoring specific responses and services to different customer segments (C). Redundant network coverage and autopilot capability do not directly pertain to the benefits of SLM with EAS as described.