Omnichannel for Customer Service is the Microsoft solution designed to meet these exact requirements. It provides a unified, modern interface within Dynamics 365 that allows agents to handle multiple customer conversations simultaneously across various channels, including chat, voice, SMS, and social media. It is built to increase agent productivity by consolidating different business applications and communication channels into a single workspace. This directly addresses the need for a single interface to manage multiple interactions and access information from various applications, fulfilling all the company's stated requirements.

B. Live Assist for Microsoft Dynamics 365 Powered by CafeX: This is a third-party solution that primarily adds live chat, co-browse, and video chat. It is not the comprehensive, first-party solution for managing all specified channels like phone and online reviews.
C. LinkedIn connector: This connector is used for integrating LinkedIn data, primarily for sales and marketing scenarios (e.g., Sales Navigator), not for managing real-time customer service interactions across multiple channels.
D. Unified Service Desk: This is a legacy desktop application framework that requires significant custom development to build a consolidated agent desktop. Omnichannel for Customer Service is the modern, cloud-based successor that provides these capabilities out-of-the-box.

1. Microsoft Learn. (2023). Introduction to Omnichannel for Customer Service. Dynamics 365 Documentation. In the "Overview" section, it states, "Omnichannel for Customer Service is a robust application that extends the power of Dynamics 365 Customer Service to enable organizations to instantly connect and engage with their customers across channels... It also provides a modern, customizable, and productive agent experience across different sessions." This confirms its role in providing a multi-session, multi-channel, single-interface solution.

2. Microsoft Learn. (2023). Agent experience in Omnichannel for Customer Service. Dynamics 365 Documentation. The "Introduction" section describes the agent interface: "The Customer Service workspace and Omnichannel for Customer Service apps provide a multisession interface that allows customer service agents to work on multiple cases and conversations simultaneously... to help them be more productive." This directly supports the multi-interaction and single-interface requirements.

3. Microsoft Learn. (2023). Overview of Unified Service Desk. Power Platform Documentation. The documentation describes Unified Service Desk as a "framework" that you use to "quickly build applications for call centers." This highlights that it is a development framework, not a ready-to-use product like Omnichannel, making Omnichannel the better recommendation.