The correct answer is: d) International migration.
International migration is the movement of people across international borders. It can be voluntary or involuntary, and it can be for a variety of reasons, such as economic opportunity, family reunification, or political asylum.
Internal migration is the movement of people within a country. It can be from rural to urban areas, or from one state to another. It can be for a variety of reasons, such as job opportunities, education, or family.
Rural-urban migration is the movement of people from rural areas to urban areas. It is a common phenomenon in developing countries, where people are often drawn to cities in search of better jobs and opportunities.
Interstate migration is the movement of people from one state to another. It is a common phenomenon in the United States, where people are often drawn to different states for job opportunities, education, or family.
In the case of people from Andhra Pradesh migrating to countries like the USA and the Gulf countries, this is an example of international migration. These people are moving from one country to another, and they are doing so for a variety of reasons, such as economic opportunity, family reunification, or political asylum.