The correct option is C Phloem
Bast fibre or skin fibre is plant fibre collected from the phloem (the "inner bark" or the skin) or bast surrounding the stem of certain, mainly dicotyledonous plants. They support the conductive cells of the phloem and provide strength to the stem. Most of the technically important bast fibres are obtained from herbs cultivated in agriculture, as for instance flax, hemp etc. So, Sunn hemp fibres are obtained from Phloem and not from leaf, mesocarp and testa. Thus, option C is correct.