The correct option is D Testa
Cotton fibres are single,
highly elongated cells derived from the outer epidermis of ovules and are
developmentally similar to the trichomes of Arabidopsis thaliana.
Cotton fibres are obtained from the surface of the seed coat (testa). It is not
a bast fibres and so is not obtain from the phloem.
So, the correct answer is
option D.