Which of the following pieces of code executes correctly?

a$.$

public static void main$($String$[]$ args$)$

$\{$

String subject;

int grade;

Scanner inputDevice $=$ new Scanner$($System$.$in$)$;

System.out.print$("$Please enter your grade $")$;

grade $=$ inputDevice.nextInt$()$;

inputDevice.nextLine$()$;

System.out.print$("$Please enter your subject $")$;

System.out.println$("$Your subject is $"+$ subject $+"$ and you got $"+$ grade $+"$ grade."$)$;

$\}$

b$.$

public static void main$($String$[]$ args$)$

$\{$

String subject;

int grade;

System.out.print$("$Please enter your grade $")$;

grade $=$ inputDevice.nextInt$()$;

inputDevice.nextLine$()$;

System.out.print$("$Please enter your subject $")$;

subject $=$ inputDevice.nextLine$()$;

System.out.println$("$Your subject is $"+$ subject $+"$ and you got $"+$ grade $+"$ grade."$)$;

$\}$

c$.$

public static void main$($String$[]$ args$)$

$\{$

String subject;

int grade;

Scanner inputDevice $=$ new Scanner$($System$.$in$)$;

System.out.print$("$Please enter your grade $")$;

grade $=$ inputDevice.nextInt$()$;

inputDevice.nextLine$()$;

System.out.print$("$Please enter your subject $")$;

subject $=$ inputDevice.nextLine$()$;

System.out.println$("$Your subject is $"+$ subject $+"$ and you got $"+$ grade $+"$ grade."$)$;

$\}$

d$.$

public static void main$($String$[]$ args$)$

$\{$

String subject;

int grade;

Scanner inputDevice $=$ new Scanner$($System$.$in$)$;

System.out.print$("$Please enter your grade $")$;

grade $=$ inputDevice.nextInt$()$;

System.out.print$("$Please enter your subject $")$;

subject $=$ inputDevice.nextLine$()$;

System.out.println$("$Your subject is $"+$ subject $+"$ and you got $"+$ grade $+"$ grade."$)$;

$\}$