The correct answer is A.
Amputation ( the removing of a limb from the body ) was a very common medical procedure during the Civil, First and Second World Wars.
A limp is amputated if its injury is beyond the body's ability to heal. The most common cause for an imputation during wartime was infection.
Some infections were so severe that no amount of medicine could treat the injury (the development of dead tissue in the wound). During a war, medical care and access to a doctor were limited. Th field lazarets were overcrowded, there was a shortage of medicine, bandages and medical equipment. There was no time to perform complicated operation. An amputation was the easiest ( but not the most painless ) way to treat an injury.
Amputation limited the number of causalities due to infection because the infection was removed with the amputated limp. The patient recovered relatively quickly and could be released from hospitals. If the amputations had not taken place, many would have died form infections that were impossible to be cured.