This chapter discusses that light sometimes acts like a photon. What is a photon?

a. a charged particle in the nucleus of every atom
b. a kind of magnetic substance found in reflective minerals
c. a self-contained "packet" of electro-magnetic energy
d. a kind of sound that is too high frequency for the human ear to hear
d. you can’t fool me. Einstein showed that photons were a mistake – they don’t exist.