The changes. You are measuring change. It could be Temperature, height, or any other form.
Answer:1 : substratum. 2 : the base on which an organism lives the soil is the substrate of most seed plants. 3 : a substance acted upon (as by an enzyme)
D) Atom... is the right option
I'm pretty sure it is B. neap tide.
If that is wrong, then it is D. spring tide.
C. Mutualistic relationship
Flowers and hummingbirds have a mutualistic relationship where both benefit. Flowers produce food in the form of nectar (sugar and water) to attract hummingbirds which, in turn, move pollen for the plant (pollination).