i think you mean antibiotic ... but Alexander Fleming was the one who advanced the antibiotic (world) and was responsible for creating these categories of medicine... this affected the 20th century because millions of people use antibiotics everyday and without them... many diseases would still affect people without a cure
Historians often rely on both primary and secondary sources when supporting an argument, since it's important to use secondary sources to put the argument in context, and primary sources in order to make an original point.
The answer would be letter A.
First obviously was his deafness. He struggled with talking to people because he could not hear what they had to say. Often he ignored others because he could not communicate that he was deaf.
Second is his love life. He did fall in love several times but because of his rank they could not be together.
Cities developed professional firefighting and police forces.
