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

After reasoning, which of the following classes is one valid superclass of 'antigen processing and presentation of endogenous peptide antigen via MHC class II'?

A. immune system process
B. regulation of apoptotic process involved in morphogenesis
C. stroma of bone marrow
D. floor plate morphogenesis

Answer: immune system process