9 .
Have a look at these sentences, which one is perfect?
At the zoo we saw giraffes, elephants, penguins, lions, camels, and snakes.
At the zoo we saw giraffes, elephants, penguins, lions, camels and snakes.
At the zoo we saw giraffes elephants, penguins, lions, camels and snakes.
At the zoo we saw giraffes, elephants, penguins, lions, camels and, snakes.