Which phrase describes the relative age of a rock?
uses the law of superposition to determine which rock is older or younger
can determine the age based on location of a rock within the same layer
requires only one rock to determine the age
can provide the exact age of a rock

Uses the law of superposition to determine which rock is older or younger

Explanation:

When you say relative age of a rock, you are determining the age of a rock relative to another rock. In the case of superposition, you are determining the relative age of a layer of rock by comparing it to the position of another rock layer.

The law of superposition states that the younger rock layers will be found higher. So the deeper the layer is found, the older the rock layer will be compared to those on top of it.  

I belive it's c

Explanation:

It origanally provides the basis for the law of superposition.

hormones in blood stream

image: dtc.ucsf.edu

endocrine glands secrete hormones into the blood stream near them; the hormones then travel in our bloodstream until it reaches its destination, called a target cell, in distance parts of the body. in the target tissue, hormones lock onto the target’s plasma membrane, called the receptor site.

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.