Unidirectional flow of water, minerals and some hormones occur through:
D) vascular tissue.
There are two types of vascular tissues in plants, xylem and phloem. xylem translocation is mainly from roots to aerial parts. It passes water with mineral salts, some organic nitrogen and hormones. Phloem translocates organic substances and some inorganic solutes first from leaves to all other parts of the plant and storage organs. Storage organs reexport organic nutrients to those parts which require the same, such as newly formed leaves and fruits. So, the correct answer is 'Xylem'.