How to solve

Tablet PC Comparison provides a wide variety of information about tablet computers. The company's website enables consu life, and CPU manufacturer. A sample of $10$ tablet computers is shown. $+$

Product Information for $10$ Tablet Computers

$\backslash$table$[[$Tablet$,\backslash$table$[[$Cost$],[($$$)]],\backslash$table$[[$Operating$],[$System$]],\backslash$table$[[$Display Size$],[($inches$)]],\backslash$table$[[$Battery Life$],[($hours$)]],\backslash$table$[[$CPU$],[$Manufacturer$]]],[$Acer Iconia W$510,599,$Windows,$10\mathrm{.}1,8\mathrm{.}5,$Intel$],[$Amazon Kindle Fire HD$,299,$Android,$8\mathrm{.}9,9,$TI OMAP$],[$Apple iPad $4,499,$iOS,$9\mathrm{.}7,11,$Apple$],[$HP Envy X$2,860,$Windows,$11\mathrm{.}6,8,$Intel$],[$Lenovo ThinkPad Tablet,$668,$Windows,$10\mathrm{.}1,10\mathrm{.}5,$Intel$],[$Microsoft Surface Pro,$899,$Windows,$10\mathrm{.}6,4,$Intel$],[$Motorola Droid XYboard,$530,$Android,$10\mathrm{.}1,9,(8)$ TI OMAP$],[$Samsung Ativ Smart PC$,590,$Windows,$11\mathrm{.}6,7,$Intel$],[$Samsung Galaxy Tab,$525,$Android,$10\mathrm{.}1,10,$Nvidia$],[$Sony Tablet S$,360,$Android,$9\mathrm{.}4,8,$Nvidia$]]$

$($a$)$ How many elements are in this data set? $$

$($b$)$ How many variables are in this data set? $$

$($c$)$ Which variables are categorical? $($Select all that apply.$)$

cost

operating system

display size

battery life

cpu manuafacturer