It is the most common type of tapetum in angiosperms, where the cells remain in their original position and later break down progressively. Among the substance released from the degenerating tapetum are pollenkitt and tryphine.

The details of event in the secretory tapetal cells of Helleborus foetidus from the premeiotic stage to the pollen maturation have been described in detail by Echlin and Godwin (1968) which are briefly stated below:

i. The cell wall is relatively thin, being composed of middle lamella and a primary wall with low content of cellulose. The cytoplasm possesses mitochondria, plastids, number of pro-Ubisch bodies and dictyosomes.
ii. Prior to meiosis the tapetal cell wall becomes thick and the cytoplasm becomes denser due to the increased number of ribosomes and pro- Ubisch bodies. Thickening is however, irregular on the wall facing the locule.

iii. During meiosis there is further increase in the number of pro-Ubisch bodies together with increase in nuclear size.

iv. During the tetrad stage the pro-Ubisch bodies are surrounded by a radiating zone of ribosomes. After separation from the tetrad the pro-Ubisch bodies pass through the tapetal cell membrane and are extruded into the space between the membrane and the cell wall where they are immediately coated with sporopollenin, and are now referred as Ubisch bodies.

v. The inner tangential wall of the tapetal cell now appears thinner and a space appears between the cell membrane and the wall. This is followed by the disappearance of the wall and a new membrane is formed around the tapetal protoplast along the thecal phase.

Secretory Tapetum
The correct answer is option 'B', secretory tapetum. The deposition of sporopollenin granules, also known as Ubish bodies or orbicules, is a characteristic feature of the secretory tapetum.

Tapetum Function
The tapetum is a specialized layer of cells found in the anther of flowering plants. It plays a crucial role in the development and maturation of pollen grains. The tapetum provides essential nutrients and metabolites to the developing pollen grains, ensuring their proper growth and viability. It also helps in the deposition of various substances, including sporopollenin granules.

Types of Tapetum
There are two main types of tapetum:

1. Amoeboid Tapetum: This type of tapetum is characterized by irregularly shaped cells with thin cell walls. The amoeboid tapetum is often involved in the synthesis and secretion of lipid-rich substances, such as pollenkitt, which contribute to the ornamentation and protection of pollen grains. However, it does not play a direct role in the deposition of sporopollenin granules.

2. Secretory Tapetum: The secretory tapetum is responsible for the deposition of sporopollenin granules, also known as Ubish bodies or orbicules, on the developing pollen grains. Sporopollenin is a highly resistant biopolymer that forms the outer layer of pollen grains, protecting them from desiccation, UV radiation, and other environmental stresses. The secretory tapetum synthesizes and releases these sporopollenin granules, which adhere to the pollen surface, contributing to its structural integrity and protection.

Conclusion
In summary, the secretory tapetum plays a vital role in the deposition of sporopollenin granules, also called Ubish bodies or orbicules, on the developing pollen grains. This process ensures the proper development, maturation, and protection of pollen grains, enabling them to fulfill their reproductive function.