What function does BYNET perform in Teradata systems?

The BYNET in Teradata serves as the communication backbone for data processing. Its primary function is to facilitate efficient data transfer between the nodes in a parallel processing environment. In the context of the question, option C highlights the BYNET's role in executing data merge functions before the results are returned to the client.

When a query is processed in Teradata, multiple nodes may handle different parts of the data simultaneously. After data is processed, the BYNET ensures that these separate pieces are merged together efficiently, making it possible to return a unified result set to the user. This merging process is critical for maintaining the integrity and performance of data transactions, especially in a system that leverages parallel processing.

Other functions, such as data integration across different databases, monitoring system performance, or managing data encryption and security, are outside the primary purpose of the BYNET. While the BYNET might indirectly support aspects of system performance and communication between nodes, its main focus and function is centered on handling data transfers and merges in a parallel processing context.