According to the Microsoft Azure AI Fundamentals (AI-900) official study materials and Microsoft Learn module “Describe features of Computer Vision workloads on Azure”, the Azure AI Custom Vision service allows users to build, train, and deploy custom image classification or object detection models. It is specifically designed for scenarios where you need a model tailored to your unique image dataset — in this case, personal digital photographs.

Custom Vision lets you upload and label your own images (for example, “family,” “friends,” “vacations,” or “pets”) and then train a model that learns to recognize those categories. The system automatically extracts relevant features from the training images and creates a model capable of classifying new images into the predefined labels. You can iteratively refine your model by adding more images or re-training to improve accuracy.

The other options do not fit this requirement:

A. Azure AI Language deals with text-based tasks such as language understanding, sentiment analysis, and key phrase extraction — not image processing.

B. Azure AI Computer Vision provides prebuilt image analysis models (e.g., object detection, tag generation, scene description), but it cannot learn custom categories unique to your dataset. It’s great for general image recognition but not for specialized labeling tasks.

C. Azure AI Document Intelligence (Form Recognizer) is used to extract information from structured or semi-structured documents such as forms, invoices, or receipts — not photographs.

Therefore, when you need to label or categorize personal photos with custom-defined tags, the right service is Azure AI Custom Vision, because it allows you to build a model trained specifically on your own collection of images.