The correct characteristic typically described for the photosphere and chromosphere would be their plasma composition.
While the photosphere is associated with visible light (often perceived as yellow or white) and the chromosphere with a reddish hue during solar phenomena like solar eclipses, the defining characteristic in terms of scientific description focuses more on their plasma nature and the physical processes occurring within those layers.
Thus, while all options have some relevance, their plasma composition is the best answer in the context provided.