Which data sharing arrangement enables computer-to-computer data transfer, usually over private telecommunication lines?

The correct answer is Electronic Data Interchange (EDI) because it specifically refers to the structured transmission of data among organizations by electronic means. EDI enables the seamless exchange of business documents and information, such as purchase orders and invoices, directly between computer systems over private telecommunications lines. This functionality facilitates more efficient communication and transactions, eliminating the need for manual data entry and reducing errors.

In contrast, other arrangements like remote procedure calls (RPC) focus on allowing one program to execute a procedure in another program located on a different computer, which doesn't necessarily imply complete data transfer for business documents. Application programming interfaces (APIs) provide a set of rules and tools for building software applications and do enable data exchange, but typically over the internet rather than specifically through private lines. File transfer protocol (FTP) is primarily a method for transferring files over a network and, while it supports data transfer, it does not inherently organize or standardize the data for business transaction purposes as EDI does.