Which XXX adds a student to the ArrayList?

public class Roster $\{$

private ArrayList$<$ Student $>$ studentList;

public void addStudent$($Student s$)\{$

XXX;

$\}$

$\}$

Select one:

a$.$ addStudent$($s$)$

b$.$ add$($s$)$;

c$.$ studentList.add$($s$)$;

d$.$ studentList $=$ s;