The data set below contains data on direct marketing campaigns of a banking institution. Clients were contacted by phone with the goal of having them subscribe to a term deposit $($that is$,$ open a certificate of deposit $($CD$)$ account$).$

$($Note: The file may not open when using Microsoft Edge. Use another browser or right$-$click "Save link as$"$ to download the data file.$)$ This data set is an example of

a$.$ cross$-$sectional data.

b$.$ time$-$series data.

c$.$ panel data.

d$.$ aggregate data.