Indicate whether the following whether the following use a nominal, ordinal, interval or ratio scale. (Justify your answer with, at least, three sentences).
a. Price on the stock market
b. Marital status, classified as “married” or “never married”
c. Whether the respondent has ever been unemployed
d. Professional rank: assistant professor, associate professor, or professor
e. Grades: A,,B,C,D, or F