The correct option is
B Bast fibres
Fibre is extracted from the phloem, or bast, surrounding the stem of certain plants (mainly dicotyledons). Most of the important bast fibres are obtained from plants cultivated in agriculture, for instance, flax, ramie, jute, kenaf, and hemp. The valuable fibres are located in the phloem.
So, the correct answer is 'Bast fibres'.