b. to transport water and nutrients
the term vascular tissues is referred to the set of tissues xylem and phloem used for conduction of food and water across the plants body.
among these, xylem plays a role in transport of water from roots to the aerial parts of plants. roots are the parts which absorb water from soil and transport to the upper parts of the plants like stem and leaves through xylem tissues.
similarly, phloem are the tissues which transport food from the leaves, because leaves are the part of plants where food is synthesized through the process of photosynthesis. this food is then transported to the other parts of the plants like stems, twigs and roots.
therefore, option b is the best option.
i believe the answer is pathogens
do not click that one it is