What fibers surround the xylem and phloem? give their functions.

The xylem fiber surround xylem and phloem fiber surround the phloem.

Explanation:

The fibers surround the xylem are xylem fibers. This is a complex plant tissue. These cells are the dead cells.  

Some of the xylem fibers have cross walls and some don't have. The xylem fibers have a protoplast in it. These fibers have thick cell walls. The xylem fibers provide mechanical support to the plant.

The phloem is surrounded by phloem fibers. The phloem fibers are associated with sclerenchyma fibers. These have thick cell walls. They become dead at maturity.  

These fibers also provide mechanical support to the plants and protect the phloem. Because phloem tissues have thin walls. The phloem fibers of jute, flax plants used for making ropes.

i think the answer is b.