Answer: QnA Maker

QnA Maker is the most appropriate Azure AI service to create a bot from a FAQ document. It allows for the building of a question and answer layer over your data, enabling easy creation and training of bots using FAQ documents. Other options like Language Understanding (LUIS), Text Analytics, and Speech are used for different AI purposes such as understanding natural language, analyzing text, and converting speech to text respectively, but they aren't specifically designed for FAQ-based bots.

Author: LeetQuiz Editorial Team