In animals, digestion functions as a mechanism for a. converting carbon dioxide into oxygen b. converting oxygen into atp c. breaking down food into small molecules d. breaking down glucose into atp

its c

Explanation:

because i said so if thats not enough

food; continues with its mastication (chewing), insalivation (mixing with the salivary secretions), degluti-tion (swallowing), and the digestion, absorption, and assimilation of those food elements that are of nutritive value

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.