Read the following question and then pick a category that describes the question.
Question: What commodity 's shortage was the largest single factor in keeping North American cars off the roads during World War II ?
What category is the question in? Choose one from Abbreviation, Entity, Description and abstract concept, Human being, Location, Numeric value. Respond with only the category and no additional text.
Entity
Numeric value, Description. (The question asks for a specific commodity shortage that had a significant impact on North American car production during WW