The correct option for the transportation of water and nutrients in woody plants is A. xylem fibres. Let's break down the reasoning behind this answer and clarify why the other options are incorrect. Explanation of the Correct Answer: A. Xylem Fibres

1. Function of Xylem:
2. Xylem is a type of vascular tissue in plants responsible for the transport of water and dissolved minerals from the roots to the rest of the plant, including stems and leaves. This process is essential for maintaining plant hydration, nutrient uptake, and overall health.
3. Xylem also provides structural support to the plant due to its lignified cell walls, which help woody plants maintain their upright position.
4. Components of Xylem:
5. Xylem consists of several types of cells, including tracheids and vessel elements, which are specialized for water conduction. Xylem fibres, while primarily providing support, also play a role in the overall function of the xylem tissue.
6. Mechanism of Water Transport:
7. Water is absorbed by the roots from the soil and then transported upward through the xylem vessels. This movement occurs due to a combination of root pressure, capillary action, and transpiration pull (the loss of water vapor from the leaves creates a negative pressure that pulls water upward).

Why the Other Options are Incorrect: B. Medullary Rays: - Medullary rays are thin sheets of parenchyma cells that extend radially from the center of the stem (the pith) to the outer layers. They primarily function in the lateral transport of nutrients and storage, rather than the primary transport of water and minerals. Therefore, they do not play a significant role in the transport of water and vapor. C. Sieve Tubes: - Sieve tubes are part of the phloem, which is responsible for the transport of organic nutrients (primarily sugars) produced during photosynthesis from the leaves to other parts of the plant. While sieve tubes are crucial for nutrient transport, they do not transport water or vapor, making this option incorrect. D. Phloem Fibres: - Phloem fibres are supportive cells found in the phloem tissue. Like xylem fibres, they provide structural support but do not participate in the transport of water or vapor. Their primary role is to strengthen the phloem, which is involved in nutrient transport, not water transport. Summary of Key Points:

• Xylem is responsible for transporting water and minerals in plants, making option A the correct choice.
• Medullary rays assist in lateral transport and storage but do not transport water.
• Sieve tubes are involved in the transport of sugars, not water.
• Phloem fibres provide support but do not transport water or vapor.

Revision Summary:

• Xylem is essential for water and mineral transport in woody plants.
• Medullary rays assist in lateral nutrient transport, not water.
• Sieve tubes transport sugars, not water or vapor.
• Phloem fibres provide structural support, not transport functions.

Understanding these concepts will help clarify the roles of different plant tissues and their functions in the overall physiology of plants.