What is one reason that a culture might develop unique characteristics?
a) the climate of the area may isolate the culture, preventing outside influences.
b) some aspect of the culture is disliked by some members, so they choose to change it.
c) a member of the culture might develop a new language and teach it to the other members.
eliminate
d) the plants and animals might be unique, and the culture is influenced by the plants and animals.

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.

Ba population changes in response to a change in environment