Vascular bundle with cambium is called

$A$ vascular bundle in which the phloem is found on both sides of the xylem is called .....

Epidermal cells modify to form $:$

Select correct features w.r.t. trichomes in the shoot system:
$(a)$ Usually unicellular
$(b)$ Branched or unbranched
$(c)$ May be secretory
$(d)$ Soft or stiff
$(e)$ Helps against transpiration

Plerome gives rise to:

The primary function of lenticels is $..........$.