In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to:

$(a)$ secretion of secondary metabolities 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

  $(c)$ and $(d)$ Only

• B

  $(d)$ and $(e)$ Only

• C

  $(b)$ and $(d)$ Only

• D

  $(a)$ and $(b)$ Only