Why was medical information gathered about each soldier (in ww2)

The reason information was gathered for each soldier was because say they are hurt in anyway then the doc will have to know what kind of medicine  that the soldier could take and what they were not able to take
the doc also would need to know what type of blood they have if the need the blood do to a injury.
hope this helps 

Iwould say a, due to the fact these routes display many things that would be useful and provide explanations for how states are known.