Which of the following is a correct implementation of getFrequencyOf

public int getFrequencyOf(T anEntry)
{
  int frequency = 0;
  Node currentNode = firstNode;
  while ((currentNode != null)) {
    if (anEntry.equals(currentNode.getData())) {
      frequency++;
    } // end if

    currentNode = currentNode.getNext();
  } // end while

  return frequency;
} // end getFrequencyOf

• public int getFrequencyOf(T anEntry)
  {
    int frequency = 0;
  
    while ((currentNode != null)) {
      Node currentNode = firstNode;
      if (anEntry.equals(currentNode.getData())) {
        frequency++;
      } // end if
  
      currentNode = currentNode.getNext();
    } // end while
  
    return frequency;
  } // end getFrequencyOf
  

• public int getFrequencyOf(T anEntry)
  {
  
    Node currentNode = firstNode;
    while ((currentNode != null)) {
      if (anEntry.equals(currentNode.getData())) {
        frequency++;
      } // end if
  
      currentNode = currentNode.getNext();
    } // end while
  
    return frequency;
  } // end getFrequencyOf
  

• public int getFrequencyOf(T anEntry)
  {
    int frequency = 0;
    Node currentNode = firstNode;
    while ((currentNode != null)) {
      if (anEntry.equals(currentNode.getData())) {
        frequency++;
      } // end if
  
      currentNode++;
    } // end while
  
    return frequency;
  } // end getFrequencyOf