The answer is caves.. i think
An atomic mass unit is a unit of measurement that is used to measure the mass of atoms. The atomic mass unit (abbreviated: amu or u) is roughly equal to the mass of 1 proton<span> or 1 neutron. The unified atomic mass unit and the dalton are different names for the same thing. The dalton name is used more over time.</span>
A and C are incorrect because they are not complete transfer of valence electrons. Ionic bonds best to form a neutral molecule
Explanation:
Fusion vs Fission
In fission, energy is gained by splitting apart heavy atoms, for example uranium, into smaller atoms such as iodine, caesium, strontium, xenon and barium, to name just a few. However, fusion is combining light atoms, for example two hydrogen isotopes, deuterium and tritium, to form the heavier helium. Both reactions release energy which, in a power plant, would be used to boil water to drive a steam generator, thus producing electricity.