Exploration of antarctica’s interior did not begin until a treaty was signed by 12 nations airplanes were strong enough to withstand the winds and cold sailors from european countries landed on pack ice tractors were brought to the continents

The answer is "airplanes were strong enough to withstand the winds and cold ".

Explanation:

the group i'm selecting: greeks.

a first group of greek immigrants came to the us in the 1850s. the second group came to america starting in the 1890s due to economic opportunities they didn't have back in their home caused by the hardships of ottoman rule. greek immigration was 90% male, many of them expected to work and return to greece after earning enough capital, but ultimately had to remain in the us after the greek genocide.