Will mark brainliest and give thirteen points if you give explanation

A. high tide (A, C)

Explanation:

High tides on points A & C occur when the moon, the Earth, and the Sun are all synced in a line.

SUN <<<  EARTH >>> MOON

they are all in a straight line, making the greatest/highest tides on the sides of the Earth. A & C represent those sides, so that is the answer.

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.