Check pic The chart above shows the relationship between the first ionization potential and the increase in atomic number. The letter on the chart that indicates the noble gases or the inert elements is -

○d
○b
○c
○a

the answer is c.the valence of the atoms combine .

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.