Hi, The atomic number of an element depends on how many protons there are in one atom of that element. If the atom has 3 protons, its atomic number will be 3.
Hope this helps! If my answer was not clear enough or you’d like further explanation please let me know.
I had to look for the options and here is my answer: The two requirements for nuclear fusion that are needed to be met in order for the elements hydrogen and helium fuse to make heavier elements are extremely high temperatures and density. Hope this helps.
