I loved it and nice Ending but ...

Rating: 6/10 (6 May 2017)

I loved the movie I loved this movie and I loved that the girlfriend turned evil at the end this was really good but I had questions that the movie didn't answer
1) why only black people !!! the movie didn't answer this question even when the actor asked this question we got no answer !!
2) when we take the man brain to replace it with the black one brain what happens to the body !!!
3) why turning grandpa and grand ma as a servant !!