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

The property 'has qualifier' applies to instances of 'Measured Characteristic', and 'CurrentDensity' is a subclass of 'Measured Characteristic'. Which class can appear as the value of 'has qualifier' for instances of 'CurrentDensity'?

A. Unit Conversion
B. Observation Collection
C. Characteristic
D. Characteristic Qualifier

Answer: Characteristic Qualifier