Two species of frogs belonging to the same genus occasionally mate, but the embryos stop developing after a day and then die. These two frog species separate by .

the postzygotic barrier called hybrid inviability

Explanation:

Some times when two members of the same genus mate occasionally then they are not able to produce a viable offspring and the offspring dye very early which is called hybrid inviability which is a postzygotic barrier.

This prevents the gene flow between the two species because the offspring fitness is very low as compared to the fitness shown by a pure breed individual. So nature does not allow the less fit breed to survive. Therefore the two frog species are separated by postzygotic barrier.  

weathering is the answer.

plant because they survive by water, sunlight, ex.

explanation: