In Japan, the burakumin

A. are the cream of Japan's racial categories, having the purest blood. constitute a numerical majority in Japan.
B. are stigmatized despite being genetically indistinguishable from other Japanese.
C. are perceived as pure Japanese, even if one of their parents is not Japanese.
D. no longer face discrimination.

B. are stigmatized despite being genetically indistinguishable from other Japanese

Explanation:

The Burakumin is a group in Japan who are considered outcasts and are ostracized and stigmatized. They fall at the bottom of the traditional Japanese social order. This is because they were historically known in Japanese feudal era to have engaged in impure occupations such as executioners, undertakers, butchers, workers in slaughter houses, and generally because these occupations are considered dirty and are tainted by death

Bottleneck effect

Explanation:

  The bottleneck effect is terms of population size is one of the concept in which there is large reduction in the population size due to the various types of environment related factors and also due to the human activities are as follows:

 According to the given question, Bottleneck effect is one of the congestion point in which the large number of species or we can say that population is killed and it also increase the genetic drift. So, the above given situation is illustrating the concept of bottleneck effect.    

 Therefore, Bottleneck effect is the correct answer.