Interfascicular cambium develops from the cell of,
A. Medullary rays
B. Xylem parenchyma.
C. Endodermis.
D. Pericycle

Hint: Interfascicular cambium is formed in the secondary growth of a plant. Secondary growth is determined by a usual increase in thickness or girth of the plant. It is caused by the cell division in the lateral meristem of the plant. Herbaceous plants mostly undergo primary growth, with little secondary growth or increase in thickness. But usually, secondary growth is occurring in the dicot plant.

Complete answer:
In woody dicots, generally the strip of cambium which is present only in between the primary xylem and phloem is called the interfascicular cambium. The interfascicular cambium is formed only from the cells of the medullary rays adjoining the interfascicular cambium in dicot stem. So this results in the formation of a continuous cambium ring in case of dicot stem in secondary growth.
More commonly in the dicot stem, during intraStelar secondary growth of the stem, there are two types of cambia are formed. A strip of cambium or ring of cambium is formed in between the xylem and phloem of a vascular bundle is called Intra fascicular cambium. Another strip of cambium or ring of cambium which is formed between vascular bundles by dedifferentiation of parenchyma tissue present in the medullary rays is called Interfascicular cambium. Both intra and interfascicular cambia join together generally to form into a ring of cambium called vascular cambium in the growth of dicot stem.

So, the correct option is A.

Note:
A cambium (or cambia), in plants having a tissue layer that provides partially undifferentiated cells for plant growth in secondary development. It is found only in the area between xylem and phloem. It forms parallel rows of cells continuously like a ring which results in secondary tissue undergrowth.