Select all that apply.

• A

  closing an open file is performed by the closefile ( ) function

• B

  the second open ( ) argument describes the open mode and defaults to `w'

• C

  if open ( ) `s second argument is `r' the file must exist or open will fail

• D

  if open ( )'s second argument is `w' and the invocation succeeds, the previous file's content is lost