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
ALL L3 morphology is a malignancy arising from which cell lineage – 
Select and explain. 
A. Mature B cell, B. Precursor B cell, C. Immature T cell, D. Mixed B cell & T cell
A: Mature B cell
Answer: A: Mature B cell 
Explanation: Cellular classification of ALL 
French-American-British (FAB) system divides ALL into three morphological subtypes.
i) LI lymphoblasts

Most common type (80-85%)
Cells have scanty cytoplasm and inconspicuous nucleoli.
Have better prognosis

ii) L2 lymphoblasts

Cells are large and more pleomorphic in size with more abundant cytoplasm and prominent nucleoli.

iii) L3 - lymphoblast

Least common
Morphology is identical to urkitt's lymphoma cells i.e., mature B cells with surface immunoglobulin positive.