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

The property 'opposite to' applies to instances of 'direction', and 'zenith' is a subclass of 'direction'. Which class can appear as the value of 'opposite to' for instances of 'zenith'?

A. escherichia coli
B. direction
C. tropical forest
D. obukhov length

Answer: direction