Question

The fuel efficiency of a car decreases as tire pressure decreases. What's the independent variable in the situation?

Answer 1

B.

the pressure is the independent variable

Explanation

The fuel efficiency of a car decreases as tire pressure decreases, in other words the efficiency depends on pressure

$\text{efficiency}\Rightarrow depends\text{ on Pressure}$

Hence,

efficiency: dependent variable

and

the pressure is the independent variable

I hope this helps you.