Task: Property Constraint Reasoning (ontology: Earth_Environment/EnvironmentOntology)

The property 'realizes' applies to instances of 'process', and 'plant structure development stage' is a subclass of 'process'. Which class can appear as the value of 'realizes' for instances of 'plant structure development stage'?

A. environmental contaminant
B. biomarker
C. amount of carbon atom in water
D. realizable entity

Answer: realizable entity