In which of these areas would you now be most likely to find the highest concentration of people who follow judaism? a) 1 b) 2 c) 4 eliminate d) 5

The answer is "Middle East". 

In Middle East "Israel" is the only country which can be considered a Jewish majority and explicitly Jewish state with over  6.5 million Jews. Along with that Palestine and some other, only 17 percent of the Jewish population is found outside of these areas and the US.