What is a primary feature of Azure Cognitive Services?

A primary feature of Azure Cognitive Services is the availability of pre-built APIs for AI capabilities. These APIs allow developers to easily integrate advanced features such as machine learning, computer vision, natural language processing, and speech recognition into their applications without needing deep expertise in AI. This access to ready-to-use tools helps accelerate the development process and enables organizations to enhance their applications with sophisticated AI functionalities quickly and efficiently.

In contrast, while real-time transaction processing, robotic process automation, and network security are important aspects of various Azure services, they do not specifically define the core offerings of Azure Cognitive Services. The focus of Cognitive Services is on providing ready-to-use APIs that facilitate the implementation of AI solutions, making option B the most relevant choice.