What are the three categories of animals permitted on board?

The correct choice identifies the three categories of animals that can accompany passengers on board an aircraft as carry-on pets, service animals, and emotional support animals.

Carry-on pets refer to domesticated animals that may travel in the cabin with their owners, generally within an approved carrier and under certain size constraints. Service animals, specifically trained to assist individuals with disabilities, have specific rights and access under laws like the Americans with Disabilities Act (ADA). Emotional support animals provide comfort to their owners but do not require specialized training to perform tasks like service animals.

This answer is accurate as it aligns with airline policies and regulations that distinguish the roles and requirements of each type of animal when traveling. Other choices mislabel or miscategorize animal types, leading to confusion about what is permitted under airline guidelines.