Answer:
According to the population census of 2011 (2068 BS), there are 123 identified caste/ethnic groups, language groups and more than a dozen of religious groups.
Answer:Habituation
Explanation: Habituation is defined as mechanism in which the person tends to reduce the response towards the stimulus due to prolonged interaction or presentation with it. It is kind of learning process that gets settles due to the repeated exposure.
The case mentioned in the question also wants to refer "nose-blindness" towards the odor as habituation because people are repeatedly exposed to the same odor that they don't notice the fragrance of their air fresheners.