Geometry Question from new Quant Problem Solving Tag

[jonestyram]

Why is the answer C and not D?

My logic is that there is no way to figure out the measure of the angles with no defined center/diameter, as well as no definition of parallel lines.

However as I am thinking about it now, it seems like the arc measure is the hint? Since both angles touch points B and D they form complementary arcs which transfer to complementary angles? Is that a thing?

Thanks in advance

[sidthakur08]

It is mostly just a conceptual thing,
“The opposite angles of a cyclic quadrilateral add up to 180°”.

Though if you want to look at the concept and how we get it, you can check out this link.