Find the approximate number of photons emitted in 1 s from a source that emits 1 W of light power at a wavelength of 500 nm:
a) 2.4 x 10¹⁸
b) 4.8 x 10¹⁸
c) 6.0 x 10¹⁸
d) 1.2 x 10¹⁹