X-rays were discovered by:

Explanation

The correct answer is A. Wilhelm Conrad Roentgen discovered X-rays on November 8, 1895, while experimenting with cathode-ray tubes. He observed a new form of invisible radiation that could penetrate various materials, naming it 'X-rays.' Roentgen's discovery had a significant impact on medical imaging and various scientific and industrial applications.Option B, De Broglie, is incorrect as he was known for his work on wave-particle duality in quantum theory, not for discovering X-rays. Option C, Young, is incorrect as Thomas Young was famous for his double-slit experiment demonstrating the wave nature of light, not X-rays. Option D, Michelson, is incorrect as Albert A. Michelson's contributions were in measuring the speed of light precisely and developing interferometers, not in the discovery of X-rays.