What two agents are the biggest proponents of chemical weathering?

Chemical weathering changes the composition of a mineral to break it down. The agents of chemical weathering include water, carbon dioxide, and oxygen. Living organisms and humans can contribute to chemical weathering

Explanation:

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.