Explanation:

Fourth option is correct.
International Organization for Migration publishes World Migration Report (WMR).
Since 2000, IOM has been producing world migration reports to contribute to increased understanding of migration throughout the world.
According to UN World Migration Report (2018) Indian Diaspora is world’s largest, with slightly more than 15.6 million people from India living overseas.
Facts related to the report-
• According to the report, Mexico has the second largest Diaspora after India followed by Russia (3rd), China (4th), Bangladesh (5th) and Pakistan (6th).The Gulf nation’s house biggest share of the Indian Diaspora — nearly 3.5 million or 22% of total Indian Diaspora.
• The global migrants figure has risen by 10% over that recorded in 2010. In other words, out of global population of 7.3 billion, one of every 30 people was migrant in 2015.
• However, if computed as percentage of world’s population, the growth of Diaspora has been largely static, from 3.2% in 2010 to 3.3% in 2015. Notably, people in working age group, between 20 to 64 years, account for nearly 72% i.e. significant chunk of international migrant population.
• Nearly half of all the international migrants worldwide in 2015 were born in Asia, primarily originating from India, China and other South Asian countries Since 1970, the US has been the main destination for international migrants.
• The number of foreign-born people residing in US has almost quadrupled from fewer than 12 million in 1970 to 46.6 million in 2015 of which nearly 2 million are of Indian origin.