The correct answer to this open question is the following.
Although there are no options attached, we can say the following.
Franz Boas is credited with developing the concept of cultural relativism. What made cultural relativism radical at that time was that cultural relativism tried to understand each form of culture in its own terms and unique characteristics.
This concept of cultural relativism is very important, although created some kind of controversy at the beginning. It states that all cultures are valid and that people have to respect other forms of thinking, act, culture, and traditions. It says that it is no good to critique another culture just because we do not know much about it or judge people from other cultures just because they do not act like us.