Debbie is basically saying, listen people can be told by doctors of how much pain is to be expected for surgery, and then they can make a decision. Animals can't do this, so pain protocols are unnecessary.
I picked E for this answer because I figured that pain protocols, as stated by Carl, initiate steps to 'minimize or alleviate pain' and thus if unalleviated pain (due to lack of pain protocol) delays the healing process, maybe pain protocols should be used?
I initially had D but I couldn't see how that was convincing. Some surgical operations on infants are painful but its not like infants are waltzing into hospitals themselves. I can see that, 'well since infants can't make these decisions, we have no choice but to do pain protocols' but isn't that a little silly? Shouldn't it be a common sense assumption that infants won't be deciding to get or not get surgery, and that an elder would and thus Debbie's argument still stands. Am I making too much of a leap in pulling outside information? I thought that perhaps I am, and that's probably why I got it wrong but wouldn't this common sense assumption apply here?