Final answer:
C3 plants typically include trees and bushes, so the plants that are not included in so-called C3 plants are cool-season grasses and grains and soybeans, which utilize the C4 or CAM pathways for photosynthesis in different environmental conditions.
Step-by-step explanation:
The question pertains to the classification of plants based on their photosynthetic process, particularly asking which plants do not fall under the category of C3 plants.
C3 plants use the C3 pathway or Calvin cycle for carbon fixation during photosynthesis, which is one of the most common pathways in plants. This pathway occurs in the chloroplasts of leaves under moderate light, temperature, and carbon dioxide conditions. It is typical of many trees, temperate climate plants, and various crops such as rice and wheat. Therefore, trees and bushes (option d) are generally considered C3 plants.
C3 plants do not include plants that use alternative pathways like C4 or CAM (Crassulacean Acid Metabolism) for photosynthesis. These pathways have adaptations for hot, arid, or variable conditions and usually pertain to cool-season grasses and grains (option b) and soybeans (option c). Thus, the correct answer to which plants are not included in the so-called C3 plants would be options b and c, as these plants have different photosynthetic mechanisms to cope with different environmental conditions.