How can the Client send language preference Information to the Server using a standard HTTP facility?

A Client wants to retrieve a representation of a resource, e.g. an XML document, localized
according to the preferences of the user. Each user is allowed to specify one or more languages,
in order of preference. Such preferences are application independent. How can the Client send
language preference Information to the Server using a standard HTTP facility?

A.
In the request body

B.
In a request header

C.
In the request line

D.
In the request URL

Explanation:
http://www.w3.org/International/questions/qa-lang-priorities.en.php (Check the answer,

first paragraph)