Red light has a wavelength of 700 nm and a frequency of 4.3 x 10^14 s^-1. What is the energy of a single photon of red light?
A. 2.85 x 10^-20
B. 2.85 x 10^19
C. 2.85 x 10^-34
D. 2.85 x 10^-19