Which solution should you recommend to meet the monitoring requirements for App2?

Azure Application Insights is the most appropriate solution for monitoring App2 because it is designed specifically for monitoring the performance and usage of applications within the Azure environment. It provides powerful capabilities such as tracking the application's availability, performance metrics, and usage patterns, which allows developers to identify and diagnose issues in real time.

With Azure Application Insights, you can gain deep insights into how your application is performing from an end-user perspective. It supports a wide range of application types, including cloud applications, web apps, and microservices, making it versatile for various application architectures. Application Insights also provides robust analytics capabilities through Application Analytics Queries, which can highlight trends and provide actionable insights into user engagement.

In contrast, while VM insights, Microsoft Sentinel, and Container insights have their benefits, they are not specifically tailored for application performance monitoring. VM insights focus on monitoring virtual machines' performance, Microsoft Sentinel is largely a security information event management (SIEM) tool, and Container insights are geared towards monitoring the performance of containerized applications. None of these options aligns with the specific needs for detailed application performance and telemetry that Azure Application Insights addresses proficiently. Therefore, recommending Azure Application Insights offers the most advantageous monitoring solution for App2.