The best answer is C.
Chloroplasts are not found in all eukaryotic cells but only in plant cells. Animal cells are eukaryotic in nature but animals do not have chloroplasts in their cells because they do not engage in photosynthesis.
Photosynthesis is the process by which plants make their own food. Chloroplasts contain chlorophyll which is essential in t trapping sunlight from which supplies the energy for photosynthesis.
Animals do not make their own food like plants but eat ready made food so their cells lack mechanisms for food manufacture.