Most primitive living vascular plants are

Which organisms died and became coal deposits?

Which of the following is the first vascular plant to be represented by an extinct group?

Given below are the stages in the life cycle of pteridophytes. Arrange the following stages in the correct sequence.
$A.$ Prothallus stage
$B.$ Meiosis in spore mother cells
$C.$ Fertilisation
$D.$ Formation of archegonia and antheridia in gametophyte.
$E.$ Transfer of antherozoids to the archegonia in presence of water.
Choose the correct answer from the options given below.

How many of the following statements are true about $Azolla$?
$(a)$ It is free-floating.
$(b)$ It has bilobed leaves.
$(c)$ It is nitrogen-fixing.
$(d)$ It is a climber.
$(e)$ It has Aerenchyma in the ventral lobe of the leaf.

In $Selaginella$,reduction division occurs during the formation of