Younger layer of secondary xylem is located
(a) In centre of stem
(b) Just outside pith
(c) Just outside vascular cambium
(d) Just inside vascular cambium

Hint: The development of the vascular cambium is started when cells between the segments of vascular tissue interface the cambia inside the segments of vascular tissue to shape a total chamber around the stem. The phones framed toward within are called as auxiliary xylem or wood and those shaped toward the outside of the cambium are called as optional phloem.

Complete answer:
At the point when this occurs, the essential xylem cells pass on and lose their leading capacity, shaping a hard skeleton that serves just to help the plant. Accordingly, in the storage compartment and more established parts of an enormous tree, just the external optional xylem (sapwood) serves in water conduction, while the internal part (heartwood) is made out of dead however basically solid essential xylem. In this way, the most youthful layer of auxiliary xylem is found right inside vascular cambium and not in focus of stem, outside essence or outside vascular cambium.

Additional information:
Meristems are grouped by their area in the plant as apical (situated at root and shoot tips), parallel (in the vascular and plug cambia), and intercalary (at internodes, or stem locales between the spots at which leaves connect, and leaf bases, particularly of specific monocotyledons—e.g., grasses). Apical meristems provide ascent to the plant body and help in the growth of the plant body. Horizontal meristems are known as optional meristems since they are answerable for auxiliary development, or expansion in stem size and thickness. Meristems structure once more from different cells in harmed tissues and are answerable for wound mending. In contrast to most creatures, plants keep on developing all through their whole life expectancy in light of the limitless division of meristematic districts.

So the correct answer is Just inside vascular cambium.

Note:
Xylem development starts when the effectively partitioning cells of developing root and shoot tips offer ascent to essential xylem. In woody plants, an optional xylem establishes the significant piece of a developed stem or root and is shaped as the plant grows in circumference and fabricates a ring of new xylem around the first essential xylem tissues. . In woody roots the vascular cambium (the horizontal meristem that offers ascend to optional phloem and auxiliary xylem) starts in the pericycle just as in the procambium; the procambium is the essential meristematic tissue between the essential phloem and xylem. The main stopper cambium is a sidelong meristem.