Visible light: refers to electromagnetic waves that can cause people's vision. By definition, which of the following statements is true? ['In the sky, many celestial bodies emitting infrared and ultraviolet rays cannot be seen with visible light optical telescopes. This shows that infrared rays and ultraviolet rays are not visible light.', "In a dark room where we can't see five fingers, we can't see anything. This does not mean that no visible light stimulates our eyes.", 'Observe that a ball is black through a color filter, which indicates that visible light at certain wavelengths causes vision in our eyes.', 'When the doctor does X-rays of the patient, he can see the image on the screen. For the doctor, the X-ray is visible light.']