Cellular respiration is best described by option 1: "Process of using chemical energy from food and oxygen molecules to power life processes."
In cellular respiration, cells convert glucose and other organic molecules into usable energy (in the form of ATP) through a series of metabolic pathways that utilize oxygen. This process is essential for producing the energy required for various biological functions. Option 2 is not accurate, as hydrogen alone does not provide the necessary energy in this context.