Gamestop Corporation (GME)

[janice shell]

She had to explain the immaterial distinction between the US market and overseas exchanges.

That is not what I "explained". At all. This is:

https://www.cmegroup.com/education/courses/introduction-to-options/understanding-the-difference-european-vs-american-style-options.html

Note:

European and American style options are not regional options. They are actually terms used to describe two different types of option exercise.

And THIS is why I posed the question:

The majority of CME Group options on futures are European style and can be exercised only at expiration. Some of the notable exceptions that have American style expiration are the quarterly options on the S&P500 futures contracts, SOFR options, and Treasury options.

Even though most CME Group options are European-style and can be exercised only at expiration, it is important for traders to understand style of option they are interested in trading.

Tell me: do you understand the difference between selling calls you've purchased, and exercising them?