Which of the following data models is eligible for a NATURAL JOIN?

a$.)$

album

album$\_$id $*$

title

artist$\_$code $($FK$)$

artist

artist$\_$code $*$

name

b$.)$

album

album$\_$id $*$

title

artist$\_$code $($FK$)$

artist

artist$\_$id $*$

name

c$.)$

album

album$\_$id $*$

title

artist $($FK$)$

artist

artist$\_$id $*$

name