Final answer:
The AFNR pathway that includes the study of animals such as small animals, horses, livestock, and poultry is known as the Animal Systems pathway, which oversees animal nutrition, genetics, behavior, and welfare along with environmental and ethical considerations.
Step-by-step explanation:
The AFNR pathway that involves the study of small animals, horses, livestock, and poultry is d. Animal Systems. This pathway is dedicated to the science and management of animals and includes various aspects such as animal nutrition, genetics, behavior, and welfare. It encompasses both companion animal care and livestock management, which requires understanding of physiology, particularly the endocrine system which is critical for animal growth and response mechanisms. Issues like drug resistance and the environmental impact of concentrated animal feeding operations (CAFOS) are also relevant concerns within this field.