Answer:
The well-being of those who remain in the sending country as a result of the migration of labor can vary depending on various factors. However, based on general observations and research, the most accurate answer would be:
A. Reduced.
Migration of labor often leads to a decrease in the well-being of those who remain in the sending country. This can occur due to various reasons such as brain drain (loss of skilled workers), decreased labor supply, increased competition for jobs, and potential negative impacts on the local economy and social structures. However, it is important to note that the effects of labor migration can be complex and context-specific, so there may be cases where the well-being of those who remain is not significantly affected or even enhanced.