Answer:
A tilted circle, or an oval.
Explanation:
Just to let you know, when I studied cross sections, they were the most annoying things I have ever studied in math, so here is my go at this:
Although I am not sure, I think the cross section is an oval. This is because the plane that cuts the cone is a little tilted, providing an oval (or a tilted circle.)
Hope that this helps you!