Why does Arabidopsis have 5 genes that code for phytochrome?

A) All 5 phytochrome absorb different types of light, maximizing sensitivity of plant to it.
B) Some of the phytochromes do not function in light absorption, but regulate other processes.
C) Several of them sense red light and the others sense far- red light.
D) They mediate different types of responses to red/far- red light.