This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
Proper management of a child with an absolute neutrophil count (ANC) of 100/mm3 would be 
Select and explain. 
A. The start of broad-spectrum intravenous antibiotics, B. Careful physical examination and chest radiograph; close observation pending result of blood cultures, C. Granulocyte transfusion, D. Nutritional support with oral iron and intramuscular injection or vitamin B12
A: The start of broad-spectrum intravenous antibiotics
Answer: A: The start of broad-spectrum intravenous antibiotics 
Explanation: A child with an absolute neutrophil count (ANC) of 100/mm3 is severely neutropenic and is at risk of death from overwhelming septicemia. Because most signs of infection (e.g., pneumonitis, pyuria) depend on the presence of neutrophils, serious infection may be present in such a patient without producing characteristic physical, radiologic, or laboratory findings. Thus, broad spectrum antibiotics (to treat a variety of possible infections) must be initiated promptly after cultures are obtained. Deferring treatment until culture results are available may result in overwhelming septicemia and death. Granulocyte transfusions usually are not beneficial in these patients because of the short survival time of the cells in the bloodstream (plasma half-life is approximately 7 hours). Iron and vitamin B12 are treatments for nutritional anemias and are of no therapeutic' value in neutropenia.