How hight the earth atmosphere extends to
i think the choices are wrong !

around 30 km

Explanation:

Earth's atmosphere is about 300 miles (480 kilometers) thick, but most of it is within 10 miles (16 km) the surface.

What i got is not any of your selection but:

- 1 million meters are the same as 1000 km and the atmosphere of the earth is not that thick

- 500m is absolutely wrong cus even normal plane flight at 10 000m

So the only option is 30 km

Hope this helped :3

answer; (d) melting of sea ice;