Fern prothallus is developed from

In ferns,young leaves are protected by

Which of the following is considered the first terrestrial plant?

Give detailed information about pteridophytes.

The evolutionary advanced features of $Selaginella$ are:
$(a)$ Heterospory
$(b)$ Endosporic development of gametophyte
$(c)$ Reduced gametophyte
$(d)$ Localization of sporangium-bearing appendages in strobili
$(e)$ Unisexual gametophytes
$(f)$ Fertilization with the help of water

The stele in the rachis of $Pteris$ is