Which groups of people most directly benefited from song innovations in the song dynasty‘s open border policy?

The options of the question are, A) soldiers. B) merchants. C) farmers. D) missionaries. E) landowners. Select all that apply.

The correct answers are B) merchants and C) farmers.

The groups of people that most directly benefited from Song innovations in the Song Dynasty’s open border policy were merchants and farmers.

The Song Dynasty was a Chinese dynasty that lasted from 960 to 1279. During this dynasty, merchants benefited from the open door policy of the empire. Merchants formed guilds that help them with trade issues. This helped commerce to developed like never before. The other group that benefited the most with the open door policy were the farmers that were able to export their products to other nations.  

i think its toxic gasses but i could be wrong

can you explain a little further maybe give multiple choice? ?