Public class Bob {
private int birthYear;
private String firstName;

public Bob()
{
birthYear = -1;
name = "Not Yet Assigned";
}
}

Which of the following constructors could be placed in class Bob shown above?

a
public Bob(int a, String b) { //implementation not shown }

b
public void Bob(int a, String b) { //implementation not shown }

c
public Bob() { //implementation not shown }

d
public Bob(birthYear) { //implementation not shown }

e
public Bob(firstName) { //implementation not shown }