According to the primordial soup model, the first organic molecules could have formed from simpler inorganic substances in Earth's early oceans, but only if there
were a source of energy to cause such chemical reactions to take place. Which are
possible sources of energy that could have led to the production of these first
precursors to life?

a. lightning and cellular respiration
b. nuclear radiation and photosynthesis
c. photosynthesis and cellular respiration
d. solar radiation, volcanic eruptions and lightning