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: Pathology
Periodic acid schiff stain shows Block positivity 
Select and explain. 
A. Myeloblasts, B. Lymphoblasts, C. Monoblasts, D. Megakaryoblasts
B: Lymphoblasts
Answer: B: Lymphoblasts 
Explanation: Lymphoblast contain cytoplasmic aggregates of periodic acid-schiff (PAS)-positive material.