. During development, some cells become liver cells, somet ells and some become muscle cells. This process is called

Cellular differentiation.

Explanation:

Cellular differentiation is the process in which a cell changes from one call type to another. Usually, the cell changes to a more specialized type. Differentiation of a multicellular organism as it changes from a simple zygote to a complex system of tissues and cell types.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.

nucleus

would be most reasonable answer tbh