What crucial problem arose during WWI regarding blood transfusions?

The situation during World War I highlighted several challenges surrounding blood transfusions, particularly the fact that many soldiers died before receiving transfusions. This issue was substantial due to the sheer scale and urgency of battlefield injuries. With numerous soldiers wounded, the need for immediate medical intervention was critical. However, the lack of efficient systems and protocols for blood transfusions meant that not all soldiers who required these lifesaving procedures could be treated in time.

While there were indeed advancements made in understanding blood types later on, at the time of WWI, the transfusion process was still developing, and the infrastructure to administer blood transfusions quickly and effectively was insufficient. This led to tragic outcomes, as many soldiers succumbed to their injuries before they could receive the necessary care. The other options, while relevant in the broader context of blood transfusions, do not capture the urgency and direct consequences experienced during the war with regard to timely treatment and the high mortality rate of those who needed urgent transfusions.