Explanation:

The palisade parenchyma is a type of tissue found in leaves that is responsible for photosynthesis. It is located in the upper layer of the mesophyll, just below the upper epidermis. This tissue is composed of elongated cells that are tightly packed together and contain numerous chloroplasts, which are the organelles responsible for capturing light energy and converting it into chemical energy.

Option D: Sorghum
Sorghum is a type of grass that is widely cultivated for its grain. Unlike most other grasses, sorghum leaves do not have a distinct palisade parenchyma layer. Instead, the mesophyll tissue in sorghum leaves is composed of irregularly shaped cells that are loosely arranged. This is an adaptation that allows sorghum plants to tolerate drought and high temperatures, as the loosely arranged mesophyll cells provide a larger surface area for gas exchange and reduce water loss through transpiration.

Options A, B, and C: Mustard, Soybean, and Gram
In contrast to sorghum, mustard, soybean, and gram leaves all have a well-developed palisade parenchyma layer. This layer is important for maximizing photosynthetic efficiency by providing a large surface area for light absorption and allowing for efficient gas exchange. The presence of a palisade parenchyma layer in these plants indicates that they are well-adapted to capturing and utilizing light energy for photosynthesis.

In summary, palisade parenchyma is absent in the leaves of sorghum (option D), while it is present in the leaves of mustard, soybean, and gram (options A, B, and C). This difference in leaf structure reflects the different adaptations of these plants to their respective environments.