Which of the following statements about dinoflagellates is correct?

• A. Dinoflagellates are a group of mostly marine, photosynthetic protists that can cause harmful algal blooms.
• B. Dinoflagellates are prokaryotic organisms lacking a nucleus.
• C. Dinoflagellates are classified as fungi due to their cell wall composition.
• D. Dinoflagellates reproduce exclusively by sexual reproduction.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand what dinoflagellates are. Dinoflagellates are a group of protists, which means they are eukaryotic organisms (they have a nucleus) and are mostly found in marine environments.
2. Step 2: Recognize that dinoflagellates are primarily photosynthetic, meaning they can produce their own food using sunlight, similar to plants. This is important because it distinguishes them from non-photosynthetic organisms.
3. Step 3: Know that dinoflagellates can cause harmful algal blooms, often called 'red tides,' which can produce toxins affecting marine life and humans. This ecological impact is a key characteristic.
4. Step 4: Eliminate incorrect statements by applying your knowledge: dinoflagellates are not prokaryotic (they have nuclei), they are not fungi (they belong to protists), and they do not reproduce exclusively by sexual reproduction (they can reproduce asexually as well).
5. Step 5: Conclude that the correct statement is the one describing dinoflagellates as mostly marine, photosynthetic protists capable of causing harmful algal blooms.