What is the purpose of the xargs command?

What is the purpose of the xargs command?

A.
It passes arguments to an X server.

B.
It reads standard input (STDIN) and builds up command lines to execute.

C.
It helps shellscripts take variable argument lists.

D.
It asks a question, graphically, and returns the answer to the shell.

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