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

The property 'has part that occurs in' applies to instances of 'occurrent', and 'process boundary' is a subclass of 'occurrent'. Which class can appear as the value of 'has part that occurs in' for instances of 'process boundary'?

A. obsolete Tropical/Subtropical Steppe Division (310)
B. obsolete pomaceous fruit extract
C. obsolete spice product
D. independent continuant

Answer: independent continuant