Step 1: Understand the conditions for human settlements.
Human settlements are influenced by factors like climate, soil fertility, land conditions, and resources.
Step 2: Analyze each option.
- Option (a): Very cool climates are a challenge for permanent human settlements but do not make them impossible.
- Option (b): Fertile soil is not a factor in Antarctica, which is largely devoid of arable land.
- Option (c): Frozen land is the correct answer, as the extreme cold and permanent ice sheets make it uninhabitable for permanent settlements.
- Option (d): Long winters alone do not prevent human settlements if other conditions are suitable.
Final Answer:
The correct answer is (c) Frozen land.