The correct answer is - B. many cultures living together in one area.
The concept of multiculturalism has been forced upon the Western societies in the past few decades, and while it has some positives in it, in practice it shows that it is not so simple to implement and to work out properly.
The multiculturalism, in essence, means multiple different ethnic or racial groups with different cultures and religions, living in the same area, while continuing to practice their own culture. This causes lots of problems in practice, because some cultures seem to not be compatible with one another at all, and also, by default it means that the different groups have different rights, different laws, different way of functioning, different perspective, and unfortunately, instead of positive, it more often brings negative effects on the societies.