In the given figure of $Sphagnum$,what do $A$ and $B$ represent?

• A
  $A$-Gametophyte branch,$B$-Sporophyte branch
• B
  $A$-Antheridial branch,$B$-Archegonial branch
• C
  $A$-Archegonial branch,$B$-Antheridial branch
• D
  $A$-Sporophyte branch,$B$-Gametophyte branch