Final answer:
Categorizing automobiles as American-made or foreign-made is an example of a nominal scale because these categories serve as labels and do not imply any numeric or ordered relationship between them. Option d is the correct answer.
Step-by-step explanation:
In the context of variables and measurement scales, categorizing automobiles as American-made or foreign-made is an example of a nominal scale. This is because this categorization is qualitative and the categories do not have a numerical value or order. A nominal scale is used for labeling variables without any quantitative value. In this case, "American-made" and "foreign-made" are simply different categories that a car can fall into, with no implication that one is greater, better, or higher than the other.
Nominal scale data is used for categorization based on attributes or qualities that are not numerical. It's important to note that unlike ordinal, interval, or ratio scales, the nominal scale does not allow for ranking or ordering of the categories. This scale is about naming or labeling. Examples of nominal scale data include categorizing smartphones by company names or classifying favorite foods. Since these categories are simply labels, they can't be used for calculations in the way that numbers can in ordinal, interval, or ratio scales.
To give you a broader context, ordinal scale data can be ordered or ranked, but the differences between the ranks cannot be measured. For instance, classifying teams in a sports league based on their performance as first, second, third, and so on, is using an ordinal scale. An interval scale includes data that can be ordered and the differences between data points are meaningful, but there is no true zero point; an example is temperature in Celsius. Lastly, ratio scale data has a true zero point, and you can perform calculations of ratios; an example would be the weight of objects.
Therefore, based on the definitions provided, categorizing automobiles by whether they are American-made or foreign-made falls squarely within the nominal scale category. To reiterate, the correct option is D. nominal.