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

After reasoning, which of the following classes is one valid superclass of 'somatic recombination of immunoglobulin gene segments'?

A. utricle of membranous labyrinth
B. enteroendocrine cell
C. rostral periventricular region of the third ventricle
D. immune system process

Answer: immune system process