I'd have to say d. the hand, because every human (for the most part, no offence intended to anyone) has a hand and is able to make good (or bad, rather) use of it. It's what a person always has access to at any given time or place, even if they don't have access to one of the other options.
If somebody gets a head injury, they may be susceptible to a concussion, brain swelling, bleeding within brain tissue, skull fracture, tissue damage, etc.
A spinal injury could cause things like, paraplegia, motor skill loss, nerve damage, etc.
Well, this sounds like something is wrong with the skin, obviously. The person should contact a dermatologist and ask for treatment. This might be shingles or a rash. The best thing to do is to contact your doctor and ask for treatment.
I hope this helps:)
(Pick me as Brainliest Please!)