Representational State Transfer (REST) is the standard interface between

A HTTP client is a software application that sends HTTP requests to a HTTP server. A HTTP server is a software application that receives HTTP requests from a HTTP client and returns HTTP responses.

The other options are incorrect because:

• Option A is incorrect because REST is not a standard interface between two machines in a LAN.
• Option B is incorrect because REST is not a standard interface between an HTTP client and a user.
• Option D is incorrect because REST is a standard interface between an HTTP client and servers.