Answer : The conversion used is,
Explanation :
The conversion used :

For example : To convert 10 feet into inches.



From this we conclude that, the conversion factor used in the numerator and denominator for 1 feet should be, 
Answer: this relationship would be mutualism
Explanation: it is a relationship where both species benefit
I beleive its A but not very sure though. If im wrong sorry. But if im right I hope it helps (: