Final answer:
In ancient Greece, settlers adapted to mountainous regions primarily through terrace farming, which created arable land on steep slopes.
Step-by-step explanation:
Settlers of ancient Greece adapted to the climate and geography of the mountainous regions through various methods. One significant adaptation was the development of terrace farming on slopes. This involved the cutting out of flat areas, or terraces, into near-vertical slopes to create arable land for agriculture. The terraces were backfilled with stones for drainage and topped with soil, making the land suitable for growing crops. This adaptation was crucial for the ancient Greeks due to the poor, rocky soil and lack of flat land. Fishing, migration to flat coastal areas, and constructing underground shelters were also strategies used by different societies facing environmental challenges, but in the case of ancient Greece, terrace farming was the key method used to deal with the tough mountainous terrain.