Why can dinoflagellate blooms be harmful to humans?
a. dinoflagellates produce toxins that kill shellfishb. during algal blooms, dinoflagellate population densities reach very high levelsc. dinoflagellate blooms are not harmful; they are just unsightlyd. people can get paralytic shellfish poisoning during dinoflagellate blooms

Dinoflagellate is a type of neurotoxin which is found in the red-tide algae.

The answer is:

d. people can get paralytic shellfish poisoning during dinoflagellate blooms

Dinoflagellate algal blooms, during red-tide, release strong neurotoxins that can be ingested by shellfish and passed on to humans who eat the infected shellfish. The most significant public health problem that has been known to  cause this harmful algae poisoning is: Amnesic Shellfish Poisoning (ASP).

step 1 ammonium can be absorbed by plants, but some is converted into nitrates which are better for plants to absorb. this is called nitrification. 2. step 2 the deer eats the plants and uses the nitrogen-containing proteins for cell growth. 3. step 3 bacteria in the soil conduct nitrogen fixation to convert nitrogen gas from the atmosphere into ammonium. 4. step 4 some of the nitrates are absorbed back into plants, but denitrification breaks down the nitrates into nitrogen gas released back into the atmosphere. 5. step 5 nitrogen is found in the urine, which gets broken down into ammonium through the process of ammonification. 6. step 6 plants absorb the ammonium and begin assimilation, the process to add the nitrogen to protein.

b is the answer and if you need further with anything message me