Answer:
<em>Once they had mastered the three kinds of Egyptian writing, nineteenth-century scholars had the key to more than three thousand years of Egyptian history.</em>
Explanation:
The cause-and-effect relationship is a type of relationship where one thing or event makes another one happen. The first thing/event is referred to as the cause, and its consequence is the effect.
The excerpt from<em> The Riddle of the Rosetta Stone </em>that shows this relationship is the fourth one: <em>Once they had mastered the three kinds of Egyptian writing, nineteenth-century scholars had the key to more than three thousand years of Egyptian history.</em>
We have two events - the 19th-century scholars mastering the three kinds of Egyptian writing, and them having the key to more than three thousand years of Egyptian history. The former is the cause of the latter: if they didn't master Egyptian writing, they wouldn't know that much about Egyptian history.
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.
Keeps overheating," I hope that helps
