Which XXX assigns the parameter to the instance member?

public class Student $\{$

private double gpa;

public void setGPA$($double gpa$)\{$

XXX

$\}$

$\}$

Select one:

a$.$ this $=$ gpa

b$.$ this.gpa $=$ gpa;

c$.$ double gpa $=$ this.gpa;

d$.$ gpa $=$ this.gpa;