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

The property 'produced by' applies to instances of 'material entity', and 'organism' is a subclass of 'material entity'. Which class can appear as the value of 'produced by' for instances of 'organism'?

A. environmental contaminant
B. acidification of an aquatic environment
C. material entity
D. acceptor

Answer: material entity