As a result of dna testing, scientists learned the black death was

a. the pneumonic plague, not the bubonic plague

b. both the pneumonic plague and the bubonic plague.

c. caused by fleas on cats and dogs.

d. caused by fleas on rats and vermin.

23. how does specialization among nations encourage interdependence? nations work together to share labor and resources to produce vital goods. nations sign treaties prohibiting taxes on imports. nations produce specific goods and then trade to obtain things they need. nations that are more developed agree to fund development in nations with limited industry.