causes the body to need increasingly larger amounts of the
drug to get the same effect that was originally produced.

Explanation:

Drugs have different effects depending on the drug itself, the person taking it and their surroundings. Learn how your body processes drugs and about the short-term and long-term effects. Taking drugs can affect not just your physical and mental health, but your whole life. Just one pill can kill.

the correct answer is:

a population changes in response to a change in the environment.

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.