Healthy everyone

The blood volume in the human body is relatively stable, and the blood volume of adults is 7% ~ 8% of body weight. Medical research has proved that if the blood loss is less than 400ml at a time, plasma and blood cells can return to normal levels in a short time through self-regulation. A healthy adult who donates 200 ~ 300ml of blood each time will not only affect his health, but also help to improve the hematopoietic function of his own hematopoietic organs.

Red blood cells contain lectins, and serum contains lectins. When red blood cells containing a (or b) agglutinin are mixed with serum containing anti-A (or anti-B) agglutinin, red blood cells agglutinate due to the interaction between relatively anti-agglutinin and agglutinin (such as A and anti-A). Aggregation of red blood cells will block small blood vessels, leading to blood circulation disorders. Then these red blood cells burst and hemolyzed. Released a lot of hemoglobin. When a large amount of hemoglobin is excreted from the kidney, it can block the renal tubule and damage the renal function, resulting in oliguria or anuria. This series of reactions will cause the following symptoms: blue skin, numbness of limbs, trembling all over, chest tightness, backache, rapid heartbeat, decreased blood pressure, and even death in severe cases. Therefore, we must pay attention to the choice of blood type during blood transfusion and follow the principle of importing the same type of blood. It can be seen that b meets the meaning of the question.

So choose: B.