Which of the following is not an observation or inference on which natural selection is based
a. population produces more offsprings than environment is able to support
b. individuals with traits well suited for a given environment are more likely to survive and reproduce
c. poorly adapted individuals will not produce any offspring to inherit their genetic traits
d. there is a variation of traits among individuals of a given population

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.