Task: Class Relation Understanding (ontology: Food_Agriculture/PlantOntology)

Which of the following classes is one valid superclass of 'pollen development stage'?

A. B enlarged microsporocyte stage
B. 2.02 main shoot and axillary shoots visible at two nodes stage
C. 4 root elongation stage
D. microgametophyte development stage

Answer: microgametophyte development stage