Why would a tissue export numerous proteins if its rough endoplasmic reticulum appears extremely rough?

The correct choice highlights the function of the rough endoplasmic reticulum (RER) in protein synthesis and export. The RER is characterized by its surface being studded with ribosomes, which are the sites of protein synthesis. When the RER appears extremely rough, it indicates a high density of these ribosomes, suggesting that the tissue is actively producing a large amount of proteins.

These proteins can serve a variety of functions, such as serving as enzymes, structural components, or signaling molecules. However, a key role of the RER is to prepare proteins for export, either to other areas within the cell or to be secreted outside the cell entirely. Therefore, a tissue with an extensive rough ER is likely specialized for the export of proteins, making the option concerning protein export the correct answer.

The other options do not align with the specific role of the rough endoplasmic reticulum as effectively. For instance, the requirement for energy production is more associated with mitochondria, not directly with the RER. Sensory functions are more typical of specialized cells (like neurons), not necessarily reflective of the function of the RER. Storage functions are provided by other cellular structures, such as vacuoles or lysosomes, rather than the