After the bite of the tsetse fly, parasites multiply in the blood of animals and
a. human’s blood
b. of humans

option B, of humans

Explanation:

Of human is correct because in the structure of sentence blood word is used preceding to the organism to which it belongs.  Thus , a connecting word is required to establish a relationship between blood and human. Therefore "of " is used before blood to connect it with the organism to which it belongs.

If blood has not been used earlier in the sentence , option A would have been correct.  

considering all explanations above option B is the right choice of answer.

se

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.