Answer:
D. Aids
Step-by-step explanation:
Aids is one of the most deadliest diseases in the world. When you contract aids, it's designed to infect the cells that try to destroy it, it's a whole zombie apocalypse in your body and you don't even know it.
It attacks and weakens the immune system, and our immune system defends our bodies against infections, but HIV is extremely strong and it over powers the system, I'm not sure if there's an immune system strong enough to fight HIV or aids.