Preference is a type of Option. Option is a different concept from Must. Must is related to Ought. 
Plastic can be Solid. you are likely to find Plastic in/at/on Cabinet. Cabinet is related to File. 
Preference --IsA--> Option <--DistinctFrom--> Must <--RelatedTo--> Ought 
Solid <--HasProperty-- Plastic --AtLocation--> Cabinet <--RelatedTo--> File 