Figure $11\mathrm{.}3$ Our first $C$ program. It prompts the user to enter a positive number and

then counts down to $0.$What happens if we change the second$-$to$-$last line of the program in

Figure $11\mathrm{.}3$ from printf$("\%$d$",$ counter$)$; to:

a$.$ printf$("\%$c

$",$ counter $+\text{'}$A$\text{'})$;

b$.$ printf$("\%$d

$\%$d

$",$ counter, startPoint $+$ counter$)$;

c$.$ printf$("\%$x

$",$ counter$)$;