Sponges are classified as animals because they cannot:

• A. reproduce sexually
• B. filter water for nutrients
• C. produce their own food through photosynthesis
• D. move actively as adults

Answer: (C)

Verified step by step guidance

1. Understand the characteristics that define animals: Animals are multicellular, eukaryotic organisms that are heterotrophic, meaning they cannot produce their own food and must obtain nutrients by consuming other organisms.
2. Recognize that sponges (phylum Porifera) are simple animals that lack tissues and organs but still meet the criteria for being classified as animals.
3. Analyze the options provided: Sponges can reproduce sexually, filter water for nutrients, and are sessile (do not move actively) as adults. These traits do not disqualify them from being animals.
4. Focus on the key characteristic: Sponges cannot produce their own food through photosynthesis. This inability to synthesize food like plants or algae is a defining feature of heterotrophic organisms, which includes all animals.
5. Conclude that sponges are classified as animals because they rely on external sources of organic material for nutrition, rather than producing their own food through photosynthesis.