Final answer:
The migrants who stay actively connected across national borders are called transnational migrants. Transnationalism involves the construction of networks that transcend nation-state boundaries and is often associated with immigrants who choose not to assimilate.
Step-by-step explanation:
The migrants who stay actively connected with social, economic, political, and religious spheres across national borders are called transnational migrants. Transnationalism refers to the construction of social, economic, and political networks that originate in one country and then cross or transcend nation-state boundaries. This concept is often associated with immigrants who choose not to assimilate or are discouraged from assimilating by the host group, leading to the development of transnational identities.