One Mole Is Defined as _______

One mole is defined as _______

A) the number of particles equal to the number of atoms in exactly 12 g of carbon-12.
B) the number of particles equal to the number of atoms in exactly 16 g of oxygen-16.
C) the number of particles equal to the number of molecules in 1kg of water.
D) the number of particles equal to the number of atoms in exactly 1 g of hydrogen-1.
E) the number of particles equal to the number of atoms in exactly 1 kg of carbon at the National Bureau of Standards.