Task: Inferred Class Relation Reasoning (ontology: Sciences/Biology)

After reasoning, which of the following classes is one valid superclass of 'B220-low CD38-positive IgG-negative class switched memory B cell'?

A. negative regulation of epithelial to mesenchymal transition
B. proximo-distal subdivision of respiratory tract
C. regulation of anterograde dense core granule transport
D. mononuclear cell

Answer: mononuclear cell