If you want to walk on the wild side, you can use the (very) old-fashioned typeglob arguments for passing something like a reference that is yet not (quite) a reference... technically... I guess... See Typeglobs and Filehandles in perldata.

>perl -wMstrict -le
"use Data::Dumper;
 ;;
 our @a = (1, 2, 3, 4);
 our @b = (9, 8, 7, 6);
 f(*a, *b);
 ;;
 sub f {
   local (*c, *d) = @_;
   print Dumper \*c;
   print Dumper \*d;
   print @::c;
   print @::d;
   }
"
$VAR1 = \*::a;

$VAR1 = \*::b;

1234
9876
[download]

(OTOH, the prototype answer given by CountZero is probably what your interviewer/teacher is looking for.)