Final answer:
The standard data format used by a web service to deliver data over a network is XML (Extensible Markup Language).
Step-by-step explanation:
A web service typically processes data from a sending application and delivers it over a network using a standard data format.
The correct answer to the question is d. XML (Extensible Markup Language). This format is widely used in web services to encode and transport data due to its flexibility and the ability to work across different platforms and programming languages.