Task: Property Constraint Reasoning (ontology: Arts_Media_Entertainment/VideoGameOntology)

The property 'unlocks achievement' applies to instances of 'instantaneous event', and 'in-app purchase event' is a subclass of 'instantaneous event'. Which class can appear as the value of 'unlocks achievement' for instances of 'in-app purchase event'?

A. Item
B. Leaderboard
C. Genre
D. Achievement

Answer: Achievement