Fact Recall About Dolphins

Maria loves to read books about animals. She enjoys visiting the library every Saturday to explore new titles. Last week, she found a book about dolphins that included fascinating facts. For example, she learned that dolphins are mammals and they can hold their breath underwater for up to 10 minutes. Maria was particularly surprised to discover that dolphins are known for their intelligence and often use echolocation to communicate.

Which of the following facts did Maria learn from the book about dolphins?