Answer: C. both visible and invisible
Explanation:
Stars not only emit light in the visible range of the electromagnetic spectrum (what our eyes can see), they also emit light that is "invisible" to our eyes, because we do not have the receptors to perceive those frequencies.
In this sense, among this invisible range is ultraviolet light and infrared, for example.
Therefore, among the proposed options, the correct one is C:
Both visible and invisible
