What is the purpose of the xargs command?

What is the purpose of the xargs command?

A.
It passes argument to an X server.

B.
It will read standard input and build up commands lines to execute.

C.
It helps shell scripts take variable argument lists.

D.
It will ask a question, graphically, and return the answer to the shell.

E.
It will allow users to specify long options for commands that normally only accept short options.