Answer
The four levels of measurements are:
a. Nominal
b. Ordinal
c. Interval
d. Ratio
Work Step by Step
a. Nominal is just a number or alphanumeric character which has no other meaning and is simply used for classification (e.g. political designations, like 'senator' or 'governor')
b. Ordinal represents some order (e.g. 'silver', 'bronze', or 'gold' metals)
c. Interval represents some distinct interval between the readings (e.g. an uber driver rating)
d. Ratio is an interval having an absolute zero value from which other values can be compared (e.g. weight of food)