The wood is actually Secondary Xylem

Wood is a complex tissue found in the stems and roots of woody plants. It is primarily composed of secondary xylem, which is responsible for the transportation of water, minerals, and nutrients throughout the plant. Let's explore why the correct answer is option 'A' - Secondary xylem.

Primary Xylem and Phloem
- Primary xylem and phloem are formed during the primary growth of a plant. They are part of the primary plant body and are responsible for the initial transport of water, minerals, and organic materials.
- Primary xylem is formed towards the inner side of the vascular cambium, while primary phloem is formed towards the outer side.
- Primary xylem consists of protoxylem and metaxylem. Protoxylem is the first-formed xylem and has narrower vessels, while metaxylem is formed later and has wider vessels.
- Similarly, primary phloem consists of protophloem and metaphloem. Protophloem is the first-formed phloem and has smaller sieve elements, while metaphloem is formed later and has larger sieve elements.

Secondary Growth and Secondary Xylem
- Woody plants undergo secondary growth, which occurs in lateral meristems called the vascular cambium and cork cambium.
- The vascular cambium is responsible for the production of secondary xylem towards the inside and secondary phloem towards the outside.
- Secondary xylem is formed by the division and differentiation of the vascular cambium cells. These cells differentiate into tracheids, vessel elements, fibers, and parenchyma cells.
- Tracheids and vessel elements are the main conducting cells of secondary xylem, responsible for the transport of water and minerals. They are characterized by their thick lignified cell walls and hollow lumen.
- Secondary xylem cells are arranged in concentric rings or layers. Each year's growth forms a distinct ring, allowing the age of a tree to be estimated by counting the number of rings.

Conclusion
Wood is primarily composed of secondary xylem, which is formed during the secondary growth of woody plants. It is responsible for the transport of water, minerals, and nutrients throughout the plant. Primary xylem and phloem are formed during the primary growth and are part of the primary plant body.

Wood is a secondary xylem..because it is formed due to presence of cambium..between primary xylem..and primary phloem.