Concept:Euglena shows both autotrophic and heterotrophic nutrition depending on the environment.
Explanation:Autotrophs prepare their own food through photosynthesis, while heterotrophs depend on external organic food.
Euglena contains chloroplasts, so in sunlight it produces food like an autotroph.
When light is absent or organic nutrients are available, it absorbs food from its surroundings like a heterotroph.
Chlamydomonas, Eudorina, and Spirogyra are green organisms that can only perform autotrophic nutrition.
Thus, Euglena is the dual organism that carries out both modes of nutrition.
Answer:C. Euglena