Answer:
frog
Step-by-step explanation:
It is given in the question that the new organism that has been discovered at Costa Rica has 5 differences from a frog. So the new organism is suggested to have been closely related to the frog species because among the other species ( that is humans, gibbons, rat ), the new organisms shows very less differences with the frog species. So it is concluded that the frog species and the new organisms are closely related.