According to Pi, a zookeeper will know he or she has created a healthy environment for the animals WHEN THE ANIMALS REPRODUCE.
For animals to reproduce and give birth to young ones, many things has to be in place, such as suitable partners, right environment, right food, etc. Animals naturally reproduce when the environment is favorable unto them. Thus, reproduction of animals in the zoo shows that the right environment has been created for the animals.
Answer:
State tests are coming up for me, as well. I don't know how late it is where you're at, but I'd suggest trying to review a few concepts you'd been struggling the most with. Make sure to also get a good sleep. I'm wishing you the best of luck on your exams, I hope you do great!! :)
90% sure it's D. And I have to make this answer long or else I can't submit it so that's why I added this whole sentence
