For each of the following, indicate whether the data are cross$-$sectional or time series. $($Iltghlight in bold the correct answer.$)$

a$.$ Weekly receipts at a clothing boutique.

i$.$ Time Series

ii$.$ Cross$-$sectional

b$.$ Monthly demand for an automotive part at Advanced Autoparts,

$6$ Time Series

ii$.$ Cross$-$sectional

c$.$ Percentage of adults who bank online.

i Time Series

ii$.$ Cross$-$sectional

d$.$ Quartenly profits of MoDonald's.

$6$ Time Series

ii$.$ Cross$-$sectional

c$.$ The age of each student taking this exam.

i Time Series

i$.$ Cross$-$sectional