You are working on creating a bot that will eventually replace the users’ call to library reception to book products available in the library. The bot is expected to process the customer’s request (text and voice request) via its integration with backend services. The flow is finalized as below. 
Step 1: The customer uses a mobile app or website. 
Step 2: User is authenticated. 
Step 3: The user requests for the information in natural language. 
Step 4: Natural language request is processed by cognitive service. 
Step 5: User reviews the response and reframes the query if required. 
Step 6: Runtime telemetry is gathered to monitor bot performance. 
Identify the correct service from the below for step 2 “User Authentication.”

Answer options:

A.Cognitive service: LUIS
B.Azure Active directory
C.Application Insights
D.Azure Bot Authenticator service

Correct Answer: B
Option A is INCORRECT. LUIS helps us build conversational applications that support natural language for communication with users. LUIS can perform extraction of the information from conversations as per the requirement.
Option B is CORRECT. Azure active directory is the azure service that helps perform identity and Access Management. Hence it performs the user validation.
Option C is INCORRECT. Applications Insights are a feature of Azure monitor that helps monitor applications performance.Application Insights facilitates anomaly detection as an important feature amongst many other features.
Option D is INCORRECT. Azure Bot Authenticator service is an invalid service. We need to use the Azure active directory for the authentication.
References: 

https://docs.microsoft.com/en-us/azure/cognitive-services/luis/
https://docs.microsoft.com/en-us/azure/active-directory/
https://docs.microsoft.com/en-us/azure/azure-monitor/app/app-insights-overview