How do migrant workers contribute to the economy of their country of employment?
has to be a written answer

Migrant workers can be more skilled, driven, or willing to take unwanted jobs than other workers. For example, many Latin American immigrants in the US are willing to take lower paid / taboo jobs, like being a janitor or handyman. In countries where the population is declining, like most of Europe, the economy doesn't collapse because migrants fill the empty spaces (think of it like Jenga).They boost the age of migrant workers. Migrant workers may also be extremely skilled, and leave their country to give their knowledge skills elsewhere, usually a more developed country (the country the emigrate from would be experiencing a 'brain drain'.) Migrants also pay more money to the government (fees, taxes etc.) than they get back in benefits.

Migrant workers can be more skilled, driven, or willing to take unwanted jobs than other workers. For example, many Latin American immigrants in the US are willing to take lower paid / taboo jobs, like being a janitor or handyman. In countries where the population is declining, like most of Europe, the economy doesn't collapse because migrants fill the empty spaces (think of it like Jenga).They boost the age of migrant workers. Migrant workers may also be extremely skilled, and leave their country to give their knowledge skills elsewhere, usually a more developed country (the country the emigrate from would be experiencing a 'brain drain'.) Migrants also pay more money to the government (fees, taxes etc.) than they get back in benefits.

Why you put last one a? i think is b.