Final answer:
Sirius A emits visible light, ultraviolet radiation, and faint X-ray emissions, with the most prominent being visible light observed from Earth through telescopes.
Thus option A and D is correct answer.
Step-by-step explanation:
The star Sirius A emits electromagnetic radiation across various parts of the spectrum, including visible light, ultraviolet radiation, and some X-rays. When we observe Sirius A from Earth using telescopes such as the Hubble Space Telescope and the Chandra X-ray Observatory, we can see the star clearly in visible light and detect its presence in other forms of radiation.
It is important to note that the X-ray emissions from Sirius A are faint compared to those from its companion white dwarf, Sirius B.
This is due to the higher temperature of Sirius B, which results in it emitting more higher-frequency radiation, whereas the light we observe from Sirius A in X-ray images could be ultraviolet light that has leaked into the detector.
Thus option A and D is correct answer.