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

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

A. radiational heating
B. direction
C. deep ocean basin
D. ion velocity

Answer: direction