The RER often occurs deep in the cytoplasm. It is particularly highly developed in the cells that synthesise and secrete proteins. These include liver cells, pancreatic cells, goblet cells, plasma cells, fibroblasts, etc.So, the correct answer is 'RER is easily observed in the cell'.

Secretory cells are specialized cells that are responsible for producing and secreting specific substances. These substances may include enzymes, hormones, mucus, or other molecules that are required for various physiological functions in the body. The secretory process involves the synthesis, packaging, and release of these substances from the cell.

The correct statement for a secretory cell from the given options is "c) Rough Endoplasmic Reticulum (RER) is easily observed in the cell." This statement is true because the rough endoplasmic reticulum (RER) plays a crucial role in the synthesis and packaging of proteins that are destined for secretion.

Explanation:

1. Rough Endoplasmic Reticulum (RER):
The rough endoplasmic reticulum (RER) is a network of interconnected membrane-bound sacs called cisternae that are studded with ribosomes on their outer surface. These ribosomes are responsible for the synthesis of proteins. In secretory cells, the RER is highly developed and easily observed under a microscope due to the presence of numerous ribosomes. The proteins synthesized by the ribosomes on the RER are then properly folded and modified within its lumen.

2. Protein Synthesis and Packaging:
The RER is involved in the synthesis of proteins that are destined for secretion. As the ribosomes on the RER synthesize these proteins, they are translocated into the lumen of the RER. Within the lumen, these proteins undergo post-translational modifications, such as glycosylation, to attain their functional structure. The RER also assists in the proper folding of these proteins.

3. Formation of Secretory Granules:
Once the proteins are properly folded and modified within the RER, they are packaged into transport vesicles. These transport vesicles bud off from the RER and are transported to the Golgi apparatus. In the Golgi apparatus, the proteins undergo further processing and sorting. During this process, secretory granules are formed, which contain the synthesized and processed proteins ready for secretion.

4. Golgi Apparatus:
Contrary to option a), the Golgi apparatus is not absent in secretory cells. In fact, it plays a crucial role in the secretory process by modifying, sorting, and packaging the proteins synthesized by the RER. The Golgi apparatus receives the transport vesicles containing the synthesized proteins from the RER. It further modifies these proteins by adding specific modifications, such as phosphorylation or sulfation. The Golgi apparatus also sorts the proteins into different vesicles according to their final destination, whether it is secretion, lysosomes, or the plasma membrane.

In conclusion, the correct statement for a secretory cell is that the rough endoplasmic reticulum (RER) is easily observed in the cell. This is because the RER is highly developed in secretory cells and plays a crucial role in protein synthesis and packaging, which are essential steps in the secretory process.