During conjugation in $Paramecium$,which of the following events occurs?

• A
  Out of the four micronuclei formed,three nuclei degenerate.
• B
  Out of the twelve macronuclei formed,four nuclei degenerate.
• C
  Zygote nucleus undergoes eight successive divisions in each conjugant.
• D
  Out of the sixteen nuclei formed from zygote,$12$ become macronuclei and $4$ micronuclei.