What does $''Y''$ represent in the given chart?

In $Ulothrix$ / $Spirogyra$,the reduction division (meiosis) occurs at the time of:

$A$ : Sexual reproduction shows considerable variation in the type and formation of sex cells in members of $Chlorophyceae$.
$R$ : It may be isogamous,anisogamous and oogamous.

Identify the given figures of algae and select the correct option.

$Chlamydomonas$,$Volvox$,$Ulothrix$,$Spirogyra$ and $Chara$ are examples of:

Consider the following statements:
$I.$ In red algae,vegetative reproduction takes place by fragmentation.
$II.$ In red algae,the food is stored as floridean starch,which is very similar to amylopectin and glycogen in structure.
$III.$ The cell wall of red algae consists of chitin.
Which of the statements given above are correct?