Answer:
B) Post-zygotic factors prevented successful reproduction. 
Step-by-step explanation:
Postzygotic factors may influence the formation of the fertile offspring. 
The postzygotic barriers basically involves the formation of the hybrid organisms which do not survive past the embryonic stages i-e hybrid inviability / the hybrid creation that is unable to form the offspring i-e sterile. 
So , in the given scenario option B )Post-zygotic factors prevented successful reproduction is the right answer .