Which one of the following phenomenon is closely associated with slow wave sleep

B i.e. Stage II Type of wave Found in Alpha (a) Wave (8-12 Hz) - Adult humans, who are awake but at rest with the mind wondering & eyes closedQ. Alpha block (a wave is replaced by fast, irregular, low voltage activity) - Arousal or Aleing responseQ - Senosry stimulation - Mental concentration as solving problem - Attention is focused on something Disappearance of a - activity Onset of sleep Reappearance of a - waves Saw tooth waves Ponto - geniculo-occipital (PCO) Spikes REMQ Theta waves Stage -I - NREMQ Stage - II - NREMQ Sleep spindles & K- Complexes Appearance of Delta (8) waves Stage - III - NREMQ Predominant Delt (8) waves Stage - IV - NREMQ