Evangelista Torricelli is famous for what discovery?

Correct option is C

Evangelista Torricelli is famous for his discovery of the principle of the mercury barometer.
 He was an Italian physicist and mathematician who lived from 1608 to 1647. In 1643, Torricelli was asked by his friend Galileo Galilei to succeed him as the professor of mathematics at the University of Pisa.
 He filled a glass tube with mercury and then inverted the tube into a dish of mercury, which caused the mercury in the tube to fall, leaving a vacuum at the top of the tube.
 This discovery was a major contribution to the fields of physics and meteorology and has had important practical applications in weather forecasting, aviation, and many other areas.