Which of the following techniques can be used to explore relationships between two nominal variables?

A) Comparing the relative frequencies within a cross-classification table.
B) Comparing pie charts,one for each column (or row) .
C) Comparing bar charts,one for each column (or row) .
D) All of these choices are true.

All of these choices are valid techniques for exploring relationships between two nominal variables. Comparing the relative frequencies within a cross-classification table can show if there is an association between the two variables. Pie charts and bar charts can also be used to visually compare the frequencies of each category within each variable, allowing for a clearer understanding of any relationships that may exist.