Alexander Fleming discovered
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Pencillin
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X-ray
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Streptomycin
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Telephone
A
Correct answer
Explanation
Alexander Fleming discovered penicillin in 1928 at St. Mary's Hospital in London when he noticed that mold (Penicillium notatum) had contaminated a bacterial culture plate and killed the bacteria. This accidental discovery revolutionized medicine and earned Fleming the Nobel Prize. X-ray was discovered by Roentgen, while streptomycin was discovered by Waksman, and the telephone by Graham Bell.