Which is the best stub for a method that calculates an item's tax?

a$.$

public static double ComputeTax$($double itemPrice$)\{$

double TAXRATE $=0\mathrm{.}0675$;

return itemPrice $*$ TAXRATE;

$\}$

b$.$

public static double ComputeTax$($double itemPrice$)\{$

double tax;

return tax;

$\}$

c$.$

public static double ComputeTax$($double itemPrice$)\{$

System.out.println$("$FIXME: Calculate tax"$)$;

return $0\mathrm{.}0$;

$\}$

d$.$

public static double ComputeTax$($double itemPrice$)\{$

double tax $=0\mathrm{.}0$;

$\}$