Jupiters atmosphere is mostly made of
a. helium
b. methane
c. ammonia
d. hydrogen

Jupiter's atmosphere is composed predominantly of hydrogen and helium, but if you have to select any one option then we can look at the percentage of existence of these elements that would be
90 percent hydrogen.
remaining 10 percent is helium 
so choose Hydrogen.

It shows that the experiment is designed properly.

Less stable  hope this