Final answer:
A nonparametric test would be used when nominal data are available.
Step-by-step explanation:
A nonparametric test would be used when nominal data are available, which means option b is correct. Nonparametric tests are used when the distribution of the population is unknown or not assumed to be normal. These tests do not rely on specific assumptions about the population distribution, unlike parametric tests.
a. it is known that the population is normally distributed
Nonparametric tests are used when the assumptions of parametric tests are not met. Parametric tests often assume that the data is normally distributed or follows a specific distribution. Nonparametric tests, on the other hand, do not rely on these distributional assumptions and are more robust to violations of normality.
Nonparametric tests are suitable for various types of data, including nominal, ordinal, interval, and ratio data. They are especially useful when the distribution of the data is unknown or not normal.