Which of these is the best implementation of this new Course behavior?

Group of answer choices

public class Course $\{$

private int numSections $=0$;

public void addSection$()\{$

numSections$++$;

$\}$

$\}$

public class Course $\{$

public int numSections $=0$;

public void addSection$()\{$

numSections$++$;

$\}$

$\}$

public class Course $\{$

public int numSections $=0$;

private void addSection$()\{$

numSections$++$;

$\}$

$\}$

public class Course $\{$

private int numSections $=0$;

public void addSection$()\{$

int numSections $=$ numSections $+1$;

$\}$

$\}$