The united states uses which source of energy to produce almost 40 percent of its electricity

Coal is responsible for 40% of the energy produced in the USA.

Explanation:

Coal is responsible for about 40% of all electricity produced in the USA, even though there are several campaigns to decrease the use of fossil fuels such as coal, for energy production, due to the growing climate changes and degradation to nature that provoke. However, coal presents itself as a cheap and easily available source of energy, which explains its widespread use in the country.

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.

correct answer is a. and d.