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

The property 'has unit' applies to instances of 'quantity', and 'electromagnetic radiation quantity' is a subclass of 'quantity'. Which class can appear as the value of 'has unit' for instances of 'electromagnetic radiation quantity'?

A. unit
B. greenhouse gas
C. combustion
D. obsolete periglaciation

Answer: unit