Final answer:
The best site for intramuscular injections in swine is the muscles of the neck caudal to the ear, as it avoids damaging valuable meat cuts and is safer for the animal.
Step-by-step explanation:
The best site to administer intramuscular injections to swine is option B, the muscles of the neck caudal to the ear. This area is preferred because it minimizes the risk of damaging valuable cuts of meat and is less likely to cause injury to the animal. It is also easier to restrain the animal for an injection in this area, compared to other sites. Injections should be given in the neck in the triangle area that is bordered at the top by the nuchal ligament (the back of the ear base), at the bottom by the shoulder, and in front of the vertebrae, ensuring the needle is inserted perpendicular to the neck to access the muscle tissue.