The answer is C. nitrogen.
Plants are main producers in ecosystems so, primary productivity of ecosystems depends on them. Carbon is necessary for plants, but it is widely present in plants. On the other hand, calcium and sodium are not as essential. However, nitrogen is important for plants because it is necessary to make proteins. Proteins take part in many different processes such as photosynthesis (this is actually primary productivity). But, nitrogen is not available to plants, they cannot absorb it simply from the air but rely on some symbiotic bacteria which are able to.
Answer:
Cyclic forms
Explanation:
The hydrates of carbon are called carbohydrates. Carbohydrates are known as saccharides. The simplest carbohydrates are the monosaccharides such as glucose, fructose. Monosaccharides are the units of polysaccharides such as starch, cellulose. Polysaccharides are long chains of monosaccharides joined by glycosidic bonds in cyclic form. The glucose molecules in polysaccharides are linked in the cyclic form. It is formed when the hydroxyl group on carbon 5 linked to the aldehyde carbon 1 .
The dirt and fragments decompose and give the plant proteins/nutrients. Soil also anchors roots down and provides some water
The answer is litter carbon dioxide bubbles
I hope that helped
