Growth rings determine

Complete the following analogy-type questions:
$(i)$ Cells of cambium between vascular bundles : Intrafascicular cambium :: Cells of medullary rays : .....
$(ii)$ Cambium cells dividing towards the pith : Secondary xylem :: Cambium cells dividing towards the periphery : .......

Narrow bands of parenchymatous tissue which pass through the secondary xylem and phloem radially are called

In old trees,the greater part of secondary xylem is dark brown and resistant to insect attack due to:
$(a)$ secretion of secondary metabolites and their deposition in the lumen of vessels.
$(b)$ deposition of organic compounds like tannins and resins in the central layers of stem.
$(c)$ deposition of suberin and aromatic substances in the outer layer of stem.
$(d)$ deposition of tannins,gum,resin and aromatic substances in the peripheral layers of stem.
$(e)$ presence of parenchyma cells,functionally active xylem elements and essential oils.
Choose the correct answer from the options given below:

$A$ nail is driven into the trunk of a $30$ year old tree at a point $1$ meter above the soil level. The tree grows in height at the rate of $0.5$ meters a year. After three years,the nail will be

Diffuse-porous wood is a characteristic feature of plants growing in .........