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: Pediatrics
A family of a child just diagnosed with acute lymphoblastic leukemia asks about the child's prognosis. Which of the following is a poor prognostic indicator ? 
Select and explain. 
A. Presence of mediastinal mass, B. Age between 1 and 10 years, C. Hyperploidy with more than 50 chromosomes, D. WBC count less than 50,000/mm3 at diagnosis
A: Presence of mediastinal mass
Answer: A: Presence of mediastinal mass 
Explanation: None