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

Which of the following classes is one valid superclass of 'sepal primordium'?

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

Answer: phyllome primordium