According to the Microsoft Azure AI Fundamentals (AI-900) official study guide and Microsoft Learn modules under the topic “Describe features of common AI workloads” and “Identify capabilities of Azure AI services”, QnA Maker is the service designed specifically to create a knowledge base (KB) or question-and-answer bot from existing content such as FAQ documents, product manuals, support pages, or structured knowledge sources.

QnA Maker enables developers to take semi-structured text (for example, an FAQ document or webpage) and automatically generate a knowledge base of pairs of questions and corresponding answers. This knowledge base can then be connected to a chatbot, typically through the Azure Bot Service, so that users can interact with it conversationally. The key advantage is that the process does not require deep machine learning or programming expertise. The service uses natural language processing (NLP) to match user queries with the most relevant pre-defined answers in the knowledge base.

In the AI-900 curriculum, this falls under the Conversational AI workload—creating intelligent bots that can respond naturally to user questions. Microsoft’s training content explains that “QnA Maker extracts pairs of question and answer from your content and builds a knowledge base that can be queried by bots and other applications.” The output, as shown in the example diagram, demonstrates how user input (the question) triggers a request to the QnA Maker API, which returns a JSON response containing the best-matched answer.

The other options are not correct because:

B. Language Understanding (LUIS) is used to interpret user intent and extract entities, not to create FAQs.

C. Text Analytics performs text extraction, sentiment analysis, and key-phrase detection but does not build a Q & A knowledge base.

D. Speech handles speech-to-text or text-to-speech, not Q & A matching.

Therefore, per the AI-900 study guide and Microsoft Learn, the verified and correct answer is A. QnA Maker.