The correct answer to the question is option 4: Meghalaya. The Nokrek Biosphere Reserve is located in Meghalaya.
Let`s briefly discuss the other options to rule them out. Option 1 states Arunachal Pradesh, which is incorrect because the Nokrek Biosphere Reserve is not located in Arunachal Pradesh.
Option 2 states Assam (Asom), which is also incorrect because the Nokrek Biosphere Reserve is not located in Assam.
Option 3 mentions Sikkim, which is incorrect as well, since the Nokrek Biosphere Reserve is not situated in Sikkim.
Therefore, after eliminating the incorrect options, we are left with option 4: Meghalaya as the correct answer. The Nokrek Biosphere Reserve is indeed located in Meghalaya.