Amagnified cross-sectional view of a horsetail stem shows the tube-shaped cells of xylem. what is their function?

The xylem is the structure of the plant that is responsible for transporting water from the ground up to the different parts of the plant. It is composed water, inorganic ions, and a number of organic chemicals.   

Xylem tissue is found throughout the plant because not only does it transport water, but it also transports the nutrients that the plant needs for different processes. Aside from being responsible for the transportation of materials, the xylem is also used to replace water that was lost during photosynthesis and transpiration. 

The correct answer is c.

Idont really understand