The answer should be A. It takes a very small amount of mass to produce a lot of energy which is displayed in Einstein's equation E=mc². E is the amount of energy given off when some mass is converted into energy.
E=the energy given off, m=the mass turned to energy (I think this is sometimes referred to as the mass defect), and c=the speed of light. Nuclear reactions do not fallow the law of conservation of mass since some of the mass is converted into energy.
I hope this helps. Let me know if anything is unclear.
One correct thging is that there are the same amount of positive and negative atoms
Atmospheric oxygen DID increase after the evolution of photosynthetic prokaryotes. So It is true.
Isotopes are the atoms of the same element with same atomic number but different mass number isotopes of same element have same chemical properties due to same number of electrons atomic number of an atom is the number of electrons protons in it and mass number is the sum of protons