JCH-NACA Animal Control Officer Practice Test

The correct choice indicates that dog fighters are allowed to apply substances externally on the outside of the dog but are prohibited from administering any substances internally. This reflects the understanding of how substances might be used to enhance a dog's performance in fighting or to mask pain, potentially leading to severe distress or injury to the animal. Allowing only external substances might be an attempt to regulate the situation while still recognizing that fighters may attempt to alter their dogs' physical condition in some way, albeit unethically.

The other options suggest varying degrees of permission for using substances, but they do not accurately capture the legal and ethical guidelines regarding the treatment of animals involved in fighting. Specifically, the idea that only approved substances could be used or that only natural substances are permitted misunderstands the inherent cruelty and unacceptability of dog fighting as a practice altogether. Therefore, the specific distinction made by the correct answer reflects the focus on the unethical practice surrounding dog fighting rather than any regulation that might standardize it.