The fuel used depends on the mass of the car. So the mass of the car is the explanatory variable which lies on the x-axis and the fuel used lies on the y-axis. So, the *mass* is the explanatory variable, and it goes on the horizontal axis. *Fuel use* is the response variable, and it goes on the vertical axis.

Graph B represents this the best because the x-axis and y-axis are correctly marked, and reasonably scaled making the graph easier to read.

Source: Khan academy

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**Making appropriate scatter plots** (practice) | Khan Academy

In these practice problems, we practice telling **good scatter plots** from bad ones.
... **Making appropriate scatter plots**. **AP**.**STATS**: UNC‑1 (EU), UNC‑1.S (LO) ...

For more information, see **Making appropriate scatter plots** (practice) | Khan Academy