For Each Bow the Romans Are Producing,they Give Up the Opportunity

For each bow the Romans are producing,they give up the opportunity to make 10 arrows.The Dacians are giving up producing 2 bows for every 40 arrows they are producing.The two nations can realize mutual gains from trade if they agree on terms of trade that are:

A) Greater than 20 arrows per bow
B) Less than 10 arrows per bow
C) Greater than 10 arrows per bow and less than 40 arrows per bow,and the Dacians produce bows
D) Greater than 10 arrows per bow and less than 20 arrows per bow,and the Romans produce bows
E) Greater than 10 arrows per bow and less than 40 arrows per bow,and the Romans produce arrows