Final answer:
Elm Co. appears to have the best return on investment ratio with a percentage of 19.4%.
Step-by-step explanation:
The company with the best return on investment ratio based on the given information is Elm Co. with a return on investment ratio of 19.4%. This ratio indicates that for every dollar invested by Elm Co., the company earns a return of 19.4 cents. In comparison, Dogwood Co. has a return on investment ratio of 11.4% and Fir Co. has a return on investment ratio of 13.7%, making Elm Co. the company with the highest return on investment.