Which leaves are used in the treatment of diabetes?

Arachis hypogea exhibits

The medicinally most important part of $Rauwolfia \text{ } serpentina$ is:

Jute is obtained from a plant which belongs to the family:

The lightest wood is......

Match Column-$I$ with Column-$II$:
Column-$I$ (Forest Type) | Column-$II$ (Dominant Tree Species)
$(I)$ Tropical Rain Forests | $(a)$ $Shorea robusta$
$(II)$ Tropical Deciduous Forests | $(b)$ $Quercus$
$(III)$ Temperate Broad-leaf Forests | $(c)$ $Cedrus deodara$
$(IV)$ Temperate Coniferous Forests | $(d)$ $Dipterocarpus$