What is responsible for the red tide phenomenon? It is a phenomenon that usually coincides with storm surges; the name comes from the red kelp that often washes ashore as a result of rough weather. Red tide occurs in patches of water where certain species of dinoflagellates flourish. They are so abundant that the water becomes discolored and takes on a red hue. Red tides occur once a year and in accordance with the lunar cycle. The water appears red as a result of reduced levels of photosynthetic pigmen

Red tide occurs in patches of water where certain species of dinoflagellates flourish.

Explanation:  

Red tides refer to the noticeable microalgae proliferation that can be recognized for being a big spot in the sea of a characteristic coloration. This phenomenon is caused by two microalgae groups: diatoms and dinoflagellates, both part of phytoplankton.

Red tides occur when certain environmental factors -such as temperature, light, nutrients availability, ph, etcetera- favor the overproduction of these organisms. These species produce toxins that turn to be dangerous for other animal species that feed on them.

Because these microorganisms produce pigments, their accumulation on the sea surface can be noticed as reddish, brown, or greenish color spots of variable extension.

the answer to your question is b