Answer: Option (a) is correct.
Step-by-step explanation:
A country has a comparative advantage in producing a commodity if the opportunity cost of producing that commodity in terms of other commodity is lower than the other country.
A country has a absolute advantage in producing a commodity whose production require less number of resources than the other country.
A country exports the commodity in which it has a comparative advantage and imports commodity in which it has a comparative disadvantage.
Therefore, if both the countries decide to trade then Belarus should export linen to Russia.