Answer:
The correct answer is B.
Explanation:
Given there is a hybrid produced between two species Rana Ridibunda and Rana Lessonae and their offspring can not reproduce, this can mean there is "Postzygotic Isolation" between the said two species. Postzygotic Isolation is defined as "not being able to have fertile offspring" and that is the case in the example. I hope this answer helps.
C. the basic unit on inheritance
D. so the exchange of gases and nutrients can happen
