Cultures most typically develop without a conscious planning (but there are exceptions! So i would say that while B) and C) are not typically or commonly true, they could be true!).
They are usually simply a product of the interaction of people and their environment.
The most reliable way in which cultures are unique is when they''re not influenced by other cultures, so the best answer is A) The climate of the area may isolate the culture, preventing outside influences.
