Two Java SE classes are declared as shown below:

public class Invoice $\{$

public static String formatId$($String oldId$)\{$

return oldId $+\_$Invoice$$;

$\}$

$\}$

public class SalesInvoice extends Invoice $\{$

public static String formatId$($String oldId$)\{$

return oldId $+\_$SalesInvoice$$;

$\}$

$\}$

Which of the following statements are true about attempts to use these classes?

a$.$ Invoice invoice $=$ new SalesInvoice$()$;

System.out.println$($Invoice$.$formatId$(1234))$;

Will output $1234\_$SalesInvoice

b$.$ SalesInvoice invoice$=$new SalesInvoice$()$;

System.out.println$($Invoice$.$formatId$(1234))$;

Will output $1234\_$SalesInvoice

c$.$ Invoice invoice $=$ new Invoice$()$;

System.out.println$($invoice$.$formatId$(1234))$;

Will output $1234\_$Invoice

d$.$ Invoice invoice $=$ new Invoice$()$;

System.out.println$(($SalesInvoice$)$Invoice$.$formatId$(1234))$;

Will output $1234\_$SalesInvoice

e$.$ SalesInvoice invoice$=$ new SalesInvoice$()$;

System.out.println$($invoice$.$formatId$(1234))$;

Will output $1234\_$Invoice