Refer back to the initial explanation you wrote in Lesson 4, on the page called Introducing Patient 23's Case Study (continued). In your initial explanation you wrote about why Patient 23 felt sick during week 3. Use what you learned from your second read of "The Human Microbiome" to revise your explanation on the lines below

the answer is c) an oak tree

my teacher would say no s

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.