Explanation:

This question evaluates understanding of clustering-an unsupervised learning technique explained in the Microsoft Azure AI Fundamentals (AI-900) official study guide and Microsoft Learn module "Explore fundamental principles of machine learning." Clustering involves finding natural groupings within data without prior knowledge of output labels. The algorithm identifies similarities among data points and groups them accordingly, with each group (or cluster) containing items that are more similar to each other than to those in other groups.
* Organizing documents into groups based on similarities of the text contained in the documents # YesThis is a classic clustering application. In text analytics or natural language processing (NLP), clustering algorithms such as K-means or hierarchical clustering are used to group documents with similar content or topics. According to Microsoft Learn, "clustering identifies relationships in data and groups items that share common characteristics." Therefore, organizing text documents based on content similarity is a textbook example of clustering.
* Grouping similar patients based on symptoms and diagnostic test results # YesThis is another example of clustering. In healthcare analytics, clustering can be used to segment patients with similar health patterns or risks. The study guide emphasizes that clustering can "discover natural groupings in data such as customers with similar buying patterns or patients with similar clinical results." Thus, this task correctly describes unsupervised clustering because it does not involve predicting a known outcome but grouping based on similarity.
* Predicting whether a person will develop mild, moderate, or severe allergy symptoms based on pollen count # NoThis is a classification problem, not clustering. Classification is a supervised learning technique where the model is trained with labeled data to predict predefined categories (in this case, mild, moderate, or severe). Microsoft Learn clearly distinguishes between clustering (discovering hidden patterns) and classification (predicting predefined categories).