Answer: The explanatory variable goes in the horizontal axis.
Step-by-step explanation:
The explanatory variable is the variable that can be manipulated in an experiment. This is also called (and more commonly) the independent variable. This is the variable we usually "input" in a system, with the objective of observing the change in the response variable (also called the dependent variable, because it depends on the independent variable).
Usually, we write the explanatory variable on the horizontal axis and the response variable on the y-axis.
Then the correct answer would be C: /.
This is only because m is defined ONLY as a response variable, there are a lot of experiments with two variables, where we can use each of the variables as the explanatory variable.
And also there are some cases where in order to make the graph easier to read, we do not use the explanatory variable in the horizontal axis, instead, we may use some transformation or something alike, but those are really special cases.
