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.

B, both the pneumonic plague and the bubonic plague, is the right answer.

Explanation:

One of the most destructive pandemics in the history of humanity. It was the first influential European explosion of plague. The plague created several ethical, cultural and financial outbursts which had serious consequences on the development of European history. As a conclusion of DNA examination, scientists discovered the Black Death was both the bubonic plague and the pneumonic plague.

answer: karl marx, max weber, and emile durkheim (the fourth could be considered georg simmel)

explanation: