How Might the Observation That the Percentage of Plant Species

How might the observation that the percentage of plant species with red foliage is greatest among high-elevation plants be explained?

A) Atmospheric composition at high elevation reduces the strength of the wavelengths that normally support photosynthesis.
B) High-elevation soils have above-average concentrations of iron, which accumulated to produce iron oxide within the foliage.
C) The red wavelengths exacerbate dehydration at high elevation, so mountain plants reflect it from their surfaces.
D) Red pigments absorb ultraviolet radiation, which is more intense at high elevation.