Answer: 1
An index of regional disparity focuses on examining the economic differences between geographical regions of a particular country.
Functional and formal regions, as well as core and periphery are not geographical regions, so they would not be studied through this type of index.
Similarities among African and Asian countries would similarly not be included because the index focuses on differences.
Finally, the Western and Eastern hemispheres are too encompassing to be successfully studied through this type of index.