Climatic variations and Human activities , i don’t know the third reason ..
Answer:
Explanation:
Heres where to get your answer
https://www.info.com/serp?q=website%20medical&segment=info.0546&s1aid=3788024678&s1cid=11804561937&s1agid=114484240723&s1kid=kwd-944088888&utm_source=adwords&gclid=CjwKCAiAm7OMBhAQEiwArvGi3IMQUyr3aRG07nCggQt-8rAAgyPT3rJedCcJxTAl1ve9LJwgIxq21RoC4yQQAvD_BwE
Stem cells can differentiate into any type of cell so they can be used to produce/repair nerve tissues. Advantage of using embryonic stem cells is that they are easier to extract than adult stem cells.