Answer:
One reason that Organism A and Organism C will be placed in different groups will be due to their MODE OF NUTRITION.
As described in the question, Organism A has an autotrophic mode of nutrition which means that it has the capability to produce its own food. Organism C is a heterotroph which means it cannot produce its own food and hence will have different properties as compared to the organism A.
The calvin cycle occurs only when Carbon Dioxide is captured