Identify the structures marked $A$ to $F$ in the given diagram.

• A
  $A$-Asymmetric nucleus,$B$-Nucleus,$C$-Generative cell,$D$-Vegetative cell,$E$-Pollen,$F$-Pollen tetrad
• B
  $A$-Pollen tetrad,$B$-Pollen,$C$-Generative cell,$D$-Vegetative cell,$E$-Asymmetric spindle,$F$-Nucleus
• C
  $A$-Pollen tetrad,$B$-Vacuole,$C$-Nucleus,$D$-Asymmetric spindle,$E$-Vegetative cell,$F$-Generative cell
• D
  $A$-Vacuole,$B$-Nucleus,$C$-Pollen tetrad,$D$-Vegetative cell,$E$-Asymmetric spindle,$F$-Generative cell