The correct option is B Lamina
Venation is the arrangement of veins and veinlets in the lamina of leaves. Hence, leaf blade or lamina should be observed to know the type of venation.
Venation is of two types, reticulate and parallel. In reticulate venation, the veinlets are arranged in the form of a network, seen mostly in dicot leaves. In parallel venation, the veins run parallel to each other, seen mostly in monocot leaves.