When we think of respiration we usually think of inhaling oxygen and exhaling carbon dioxide. Assuming that all of the CO₂ we exhale is waste from cellular respiration, how does the carbon atom in CO₂ enter the body? Provide a explanation please<3

According to the rna world hypothesis, rna acted as the genetic material and catalyzed reactions in ancient cells. what conclusion can you draw from this?               a.  this implies that dna and proteins aren't essential in cells today.    b.  this implies that rna can catalyze any chemical reaction that enzymes catalyze.    c.  this implies that if a cell has a problem with its dna, its rna can compensate for the damaged dna.    d.  this implies that dna and proteins evolved after rna.