Answer:
Your answer should be A on the first two, and b on the third!!
Explanation:
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<span>protista is a producer because it is a plant</span>
The correct answer is (d.) proteins. Higher organisms use nitrogen to make their protein. Food that is containing protein also involves nitrogen in it. Protein also has amino acids that contain nitrogen in it which is a necessary essential nutrient for the body.
They evolved during the Cambrian explosion.
