B - pig is often used to model human body systems.
The correct answer is B - pig. Pigs are often used as a model species for studying human body systems and diseases due to their similarities to humans in terms of anatomy, physiology, and organ size. This makes pigs a valuable animal model for medical research and drug development. To find the answer to this question, you could have searched for "animal model for human body systems" or something similar in a search engine. The search results would have provided information about pig being commonly used as a model organism in biomedical research.
