If your backup is based upon a cold backup, and you need to restore a lost datafile, you need to restore the datafiles and control files (common perception is that redo logs need to be copied for a cold backup, but not necessary).

You can't just restore the one datafile because the SCN's in it will be out of sync with the rest of the database. That eliminates #2.

A backup consists of copying the datafiles, control files, init.ora file and archive log files. This eliminates #4 - you don't backup online redo logs.

You don't "restore" archive log files - you apply them. Picky wording, but it eliminates #1.

#3 would be the most correct answer.