Which organ is responsible for sexual reproduction in pteridophytes?

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.

To which of the following groups would you assign a plant that has a vascular supply,lacks ovules,and reproduces by means of spores?

Which of the following helps in coal formation?

$Selaginella$ is heterosporous. It produces two types of spores. The microspore develops into microgametophyte and the megaspore develops into megagametophyte. With respect to gametophyte,which one statement is correct?

The number of functional megaspores in $Selaginella rupestris$ is: