3) Knowledge is limited on the relation between weight and non-transportation costs in nearly all subclasses.
The reason for the lack of knowledge is because the relationship between non-transportation costs and weight wasn't something that people thought was worth exploring.
mnli hypothesis: The reason for the lack of knowledge is because the relationship between non-transportation costs and weight wasn't something that people thought was worth exploring. premise: 3) Knowledge is limited on the relation between weight and non-transportation costs in nearly all subclasses.