PLZ HELP ME WILL MARK BRAINLYEST

Which of the following would be the best way to determine whether a cell belonged with Archaea or Bacteria?

Check to see if it can form a capsid around itself since only Bacteria can do that.
Test to see if it can survive in harsh environments since only Archaea survive these.
Test for the presence of a special form of RNA polymerase because only Bacteria has this.
Check to see if it has a nucleus because only Archaea have nuclei.