[Solved] Which of the following produces a substantial increase in the caloric intake of laboratory rats and a significant increase in their body weight? A) removing thiamine from their usual laboratory chow B) adding thiamine to their usual laboratory chow C) offering them a cafeteria diet, rather than their usual single-chow laboratory diet D) sham feeding them E) both C and D Phenotype: The observable characteristics or traits of an organism, resulting from the interaction of its genotype with the environment. Visible Structure: The physical or organizational form of something as it appears to the naked eye. Organism's: Refers to any individual living entity, from single-celled microorganisms to plants and animals, including humans. Observable Characteristics: Traits or features that can be seen or measured directly.