Final answer:
The true statement about some photosynthesizing animals is that they incorporate chloroplasts into their cells to carry out photosynthesis (Option A). These animals are not considered true autotrophs as they depend on chloroplasts from other organisms.
Step-by-step explanation:
The correct statement regarding some photosynthesizing animals is A. These animals carry out photosynthesis through the chloroplasts they incorporate into their cells. This process, historically associated with plants and some protists like algae, involves capturing sunlight to convert carbon dioxide and water into glucose, and releasing oxygen as a byproduct. While true autotrophs such as plants and algae contain their own chloroplasts, some animals can acquire chloroplasts through eating and incorporating those from algae, allowing them to benefit from photosynthesis. An example of this is the sea slug Elysia chlorotica, which integrates chloroplasts from the algae it consumes into its own cells.
It is essential to clarify that while these animals utilize photosynthesis, they are not considered true autotrophs, as their ability to perform photosynthesis is dependent on the acquired chloroplasts from other organisms. Therefore, options B, C, and D are incorrect as they do not accurately describe the nature of photosynthesizing animals. Option B is incorrect because photosynthesis does not occur in the mitochondria. Option C is not true for animals as they typically cannot perform photosynthesis on their own. Lastly, option D is incorrect because there are multicellular organisms, not just single-celled ones, that can photosynthesize, like some species of algae.