It is not common but yes an ab parent can have an O child
I think the correct answer from the choices listed above is option C/ One reason that a product does not always form is due to unfavorable geometry of the reactants involved. When the geometry is not good for substances to react then no reaction can occur although there is enough energy present.
Higher trophic level is further up the food chain. Further up you go there are less and less competitors. So the answer is true
