WebSQL is a SQL-like （） language for extracting information from the web. Its capabilities for performing navigation of web （） make it a useful tool for automating several web-related tasks that require the systematic processing of either all the links in a（） , all the pages that can be reached from a given URL through （） that match a pattern, or a combination of both. WebSQL also provides transparent access to index servers that can be queried via the Common （） Interface.

make it a useful tool for automating several web-related tasks that require the systematic processing of either all the links in a（）

A．hypertext

B．page

C．protocol

D．operation