The market will resolve positively when human population in a given year for the first time (after the creation of the question) is lower than in the previous year, according to https://ourworldindata.org/population-growth or an equivalent source.

The "world population" is a number of biological humans living on Earth. This does not include AIs, ems and people living on other planets.

If the first such year is say 2040, i.e. population in 2040 is lower than in 2039, then "Before 2040" will resolve as NO (because 2040 is not before 2040), but 2050 and subsequent options will resolve as YES.

If the population never shrinks, all the answers will resolve as NO (and possibly I will add more options further in the future).

I do not bet on my own questions.