Answer
a. $B$
b. $VI$
Work Step by Step
In the xz (y=0) and yz (x=0) planes, traces are parabolas. This is graph B.
Level curves:
when $x=\pm 1$ or $y=\pm 1$, z is zero,
(no level curve crosses these lines)$\rightarrow$(VI)
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.