In $Funaria$ and $Pteris$,both sperms are released near the archegonium of $Pteris$. Only $Pteris$ sperms enter the archegonium because:

• A
  $Pteris$ archegonium repels $Funaria$ sperms.
• B
  $Pteris$ sperms destroy $Funaria$ sperms.
• C
  $Funaria$ sperms are less motile.
• D
  $Pteris$ archegonium secretes chemicals that attract only $Pteris$ sperms.