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

Astudent wants to test the hypothesis that fertilizer improves the growth rate of grass seeds. to test this hypothesis, the student put the same amount of grass seed in 3 containers with the same type of soil. the student measured the growth at the end of the week. all plants received equal amounts of water and sunlight. if you were asked to graph this data, what would you place on the x-axis? a. fertilizer b. water c. plant growth d. week one