Which line in the following code makes use of the implicit parameter?

public class MultiColorPen $\{$

public String color;

public boolean isRed$()\{$

String redColor $=$ "red";

String currentColor;

currentColor $=$ this.color;

return currentColor equals $($redColor$)$;

$\}$

$\}$

$($A$)$ Line $4$

$($B$)$ Line $5$

$($C$)$ Line $6$

$($D$)$ Line $7$

$($E$)$ Line $2$