The default constructor sets x and y to (0, 0) by calling the second constructor. What could be used to replace /* missing code */ so that this works as intended?

a = 0; b = 0;

this (x, y);

this(0, 0);

x = a; y = b;

a = x; b = y;

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Which of the following correctly implements a mutator method for Point?

public double getX() { return x; } 

public void setCoordinates (double a, double b) { x = a; y = b; } 

None of the items listed.

public double getX() { return a; } 

public void setCoordinates (double a, double b) { Point p = new Point(a,b); }