Mature wood stem has a peripheral water proof tissue with opening in the form of scars on its surface. They are

Root hairs are the

Vessels are not present in the xylem of

Subsidiary cells are the specialised cell in the

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