# Chapter 13 - Section 13.1 - Functions of Several Variables - Exercises - Page 682: 31

$\bf{f}$

#### Work Step by Step

We can see that there are two humps when we look at the graph of the 3D surface in $\bf{f}$. This shows that the graph of the 2D level curves has two big circular rings. Hence, our correct option is $\bf{f}$.

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