The initial test results of an EPA study in 1989 and 1990 were not conclusive about the value of biostimulation of indigenous microbes and about the use of exogenous bacteria for remediation. In contrast, a later field study in Delaware reached the following conclusions:a. Biostimulation can slow down hydrocarbon removal. b. Exogenous bacteria outcompete indigenous bacteria. c. Biostimulation can accelerate hydrocarbon removal. d. Addition of exogenous bacteria leads to faster hydrocarbon cleanup than biostimulation.

Explanation:

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.

the correct option is option d