What atomic nucleus has the fewest protons

Hydrogen-

Hydrogen is the answer because the number of protons is the atomic number.  All the elements have different atomic numbers and hydrogen has the least with an atomic number of 1.

Both models are effective because they show the valence electrons, and these valence electrons indicate the reactivity of an element.

There is no reason to think the results are biased or not conducted properly but you should not assume the results are correct just because they were done in a laboratory so the answer would be c. it is likely to be reliable because the results support the conclusion presented.