D. Nucleus
Please give brainliest answer <3
The correct word to fill the gap is pathogens.
<h3>What are pathogens?</h3>
Pathogens are microbes that are capable of causing diseases or abnormalities in people that are healthy.
Microbes that are not capable of causing diseases are referred to as non-pathogenic.
It is derived from the Greek words "pathos' which means 'suffering' and 'genes' which means 'producer of'.
More on pathogens can be found here: brainly.com/question/18918957
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If not multiple choice, Probably insects and humans would last the longest
