I'm going to have to go with red because in the question, it says "What color is a red giant?"
Well its not always red, it might also be white or blue indicating that its bright and hot. But it is also red.
If you mean "color", they are red (no surprise there, then).
Red,white,and blue
Blue and Red
No. Unless a star is a red giant (in which case it is old and dying) a red color does not indicate anything about its age.
Royal Blue, Red, Gray, and a little white
Speaking in astronomical terms there is no determined color for old dying stars. It just matters what type of star it is. For example, red giants like Betelgeuse or Antares are the most common stars these red giants also are in the same class as hyper giants a more massive red star. They generally go from a living bright orange to a dying dark red.
They should be playing in their home colors, blue,white and red.
white jersey with red numbers
Red giants are so named because they appear predominantly red in color due to their relatively cooler surface temperatures compared to other stars. The color of a star can indicate its temperature and age.
red giants
Small cool stars, such as red dwarfs, are typically red or orange in color. This is because their surface temperatures are relatively low, causing them to emit more red and orange light compared to other colors.
Stars that are the least hot, such as red dwarfs and red giants, appear red in color. This is because they emit more red light due to their lower temperatures compared to hotter stars that emit more blue and white light.