What do an electron and a neutron have in common?
Marie discovers boxes of elements in a storage room. The boxes do not say which elements they contain, but they do have information about their locations on the periodic table. What kind of information would allow Marie to determine which boxes contain the most reactive elements?

i'm assuming that the correct answer is indeed the first one/ "a"..

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.