Because they would need to compete over resources.
<u>C. Interspecific competition</u> in ecology, is a form of competition in which individuals of different species compete for the same resources in an ecosystem (e.g. food or living space). This can be contrasted with interspecific cooperation, a type of symbiosis.
Black death, also known as the bubonic plague was one of the worst pandemics that ever happened, killing around 1/3 of Europe's population. It spread to Europe in the mid 1300's from China.
Black death victims were treated through magic, witchcraft, prayer and other methods. As for the two other options, they used medicine, but not antibiotics and radiation hadn't been discovered yet (it was discovered in the 1900's)
They are related because the high pitch sounds correspond to the sound waves which give high and low frequencies.