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

The property 'was performed by' applies to instances of 'process', and 'reaction' is a subclass of 'process'. Which class can appear as the value of 'was performed by' for instances of 'reaction'?

A. north latitude line
B. non methane volatile organic compound
C. exhaustive search
D. agent

Answer: agent