Which property of an ancient rock allowed scientists to determine that Earth was at least 4.3 billion years old?

Tolerance to high levels of salinity

If a hydrogen atom is neutral, it must also have  one electron. an oxygen atom (o) has an atomic number of eight (8). this means a neutral oxygen atom has eight protons and eight electrons. the element actium (ac) has an atomic number of 89, so it has 89 protons and 89 electrons in a neutral atom

D. is the answer hope that you

What do you mean by that? like the contents? the thc level?