The Choice B is the best answer because it is concise. It does not repeat the idea of addition.
According to the statement
we have to find that the out of given options which is correct for replace the words in the passage.
So, For this purpose, we know that the
In the passage ,
Choices A, C, and D are incorrect because they are repetitive. The conjunction “and” is sufficient after “they added just nitrates” to indicate that “a source of carbon” was also added. Choice A needlessly contains “was added.” In choice C “plus also” and in choice D “also adding” are similarly repetitive.
So, The Choice B is the best answer because it is concise. It does not repeat the idea of addition.
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