Correct Answer: Henri Becquerel

Solution : The correct answer is Henri Becquerel

Henri Becquerel Discovers Radioactivity. In one of the most well-known accidental discoveries in the history of physics, on an overcast day in March 1896, French physicist Henri Becquerel opened a drawer and discovered spontaneous radioactivity.

Using a method similar to that of Roentgen, Becquerel surrounded several photographic plates with black paper and florescent salts.

With the intention of further advancing the study of x-rays, Becquerel intended to place the concealed photographic paper in the sunlight and observe what transpired. Unfortunately, he had to delay his experiment because the skies over Paris were overcast.

Final answer is Henri Becquerel