The statement that best explains why hydrogen’s atomic number is equal to its mass is:
Hydrogen does not have any neutrons.
This is because the atomic number of hydrogen is 1, indicating it has one proton, and its most common isotope also has no neutrons, giving it an atomic mass of approximately 1 (specifically about 1.008, but rounded to 1 for the simplest isotope, protium). The other statements do not accurately explain the relationship between atomic number and mass for hydrogen.