A. the moon's gravitational pull on earth causes water to bulge on two sides of the earth
In mineralogy and crystallography, a crystal structure<span>is a unique arrangement of atoms in a </span>crystal. Acrystal structure<span> is composed of a unit cell, a set of atoms arranged in a particular way; which is periodically repeated in three dimensions on a lattice.
Crystals create a harder more fitting structure so they tend to be a lot stronger than other compounds or elements</span>
You would want to make sure that you have controlled the variables properly, and if you determine that you did then you would repeat the experiment to be sure of the results.
Physical property is C.Density