public abstract class Person $\{$

private String firstname;

private String lastname;

public Person $($String first, String last$)$

$\{$

firstname $=$ first;

lastname $=$ last;

$\}$

$//$ getters for firstName and lastName

public String getFirstName $()$

$\{$

return firstname;

$\}$

public String getLastName $()$

$\{$

return lastName;

$\}$

public abstract String fullName$()$;

$\}$

$**$AND$**$

public class PersonName extends Person

$\{$

public PersonName $($String first, String last$)$

$\{$

super $($first$,$ last$)$;

$\}$

$//$ missing code

$\}$

What is the code for the proper $"//$missng code"?

a$.$ public String FullName $($String first, String last$)$

$\{$

return first $+""+$ last;

$\}$

b$.$ public String FullName$()$

$\{$

return firstName $+""+$ lastname;

$\}$

c$.$ public String fullName $($Person p$)$

$\{$

return p$.$firstName $+""+$ p$.$lastName;

$\}$

d$.$ public String fullName $()$

$\{$

return getFirstName $()+""+$ getLastName$()$;

$\}$

e$.$ public abstract void fullname$()$

$\{$

return firstName $+""+$ lastName;

$\}$

A$)$ Choice a

B$)$ Choice b

C$)$ Choice c

D$)$ Choice d

E$)$ Choice e