The correct answer is A. were discovered by accident
Explanation:
X-rays are a type of radiation mainly used for medical uses as this radiation allow doctors to create images of inner structures that are helpful for diagnosis, also, X-rays are used as part of radiotherapy to treat cancer. Additionally, X-rays were discovered in 1895 by Wilhelm Rontgen who discovered them by accident as he studied electrical discharge tubes and noticed there was an unknown or "x" type of radiation, based on this, he described X-rays and even use them to create an image of his hand. Thus, the answer is X-rays were discovered by accident.
