Consider the following class:

What line of code should be placed in the blank to create a class variable that keeps track of the most recently used registration identifier?

Question $3$ options:

a$)$

$\_$lastID $=0$

b$)$

Pet.append$(\_$lastID$)$

c$)$

Pet.$\_$lastID $=0$

d$)$

self.$\_$lastID $=0$

e$)$

None of the above