Animals breathe oxygen and release carbon dioxide during cellular respiration according to the equation below. How much oxygen is needed to produce 120 grams of carbon dioxide?

elements make up everything, and they combine to make compounds.

the answer is c

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.