Today, the most accurate conclusion we have about the Black Death is that it was

The Black Death was caused by the bacterium Yersinia pestis (misspelled in choice B as “yersina pestus”). It spread mainly through infected fleas, often carried by rodents, rather than through polluted air or simply through contact with unclean people. Choice A is not the best answer because it incorrectly identifies fleas on dogs and cats as the cause’s main route.

AI-written and checked against the verified answer.