An organization needs to train a machine learning model to categorize (Digital Leader)

Correct answer: B) AutoML Vision.
Here's why:

A) Video Intelligence API: This API is primarily designed for analyzing and extracting insights from video content, such as detecting objects, scenes, and activities within videos. While it can be useful for certain tasks, it's not specifically tailored for training machine learning models on photographs.

B) AutoML Vision: AutoML Vision is a service that allows users to train custom image classification models without requiring deep machine learning expertise. It simplifies the process of building and deploying custom models for tasks such as categorizing photographs by automatically handling tasks like data preprocessing, model training, and deployment.

C) BigQuery ML: BigQuery ML is a service that allows users to create and execute machine learning models directly within Google BigQuery using SQL queries. While it's powerful for performing machine learning tasks on structured data stored in BigQuery tables, it's not specifically designed for training models on image data like photographs.

D) Looker: Looker is a business intelligence and data analytics platform, not a machine learning service. While it can visualize and analyze data, it's not suitable for training machine learning models on photographs.

Therefore, B) AutoML Vision is the most appropriate Google Cloud product or service for the organization to use for training a machine learning model to categorize photographs.