Chi-square goodness-of-fit test is applied when t one categorical variable is selected from a single population. It tests whether the distribution of this single categorical variable follows the
theoretical distribution.

It determines whether observed counts differ significantly from expected counts if the proposed distribution was the true distribution.

Hence, the correct option is one categorical variable.

It determines whether observed counts differ significantly from expected counts if the proposed distribution was the true distribution.

Hence, the correct option is one categorical variable.