A) The great dane might kill or eat the dacshund.
B) A male dachsund would have difficulty breeding with a female great dane.
C) The resulting puppies might be too big to finish development when the mom is the dachsund.
D) The two breeds are so different that structurally, the resulting puppies would not develop correctly before birth, or would not survive very easily after birth.
E) All of these answers.