A type of strong chemical bond in which two atoms share one or more pairs of valence electrons. Two or more atoms held together by covalent bonds. The attraction that exists between opposing (positive and negative) charges within the atom.
The rigth answer is D.
The wavefront or wavefront is an equal phase surface of a wave, i.e., these points have the same travel time from the source. The concept is used to describe the propagation of waves such as sound or electromagnetic radiation (light, radio waves, etc.). In a homogeneous and isotropic medium, in which the waves propagate without deformation, two types of particular waves are distinguished according to whether the wavefronts are spheres (spherical wave) or planes (plane wave).
<span>The statement "Abnormal cells crowd out cells and steal nutrients" is true. Abnormal cells are the cells that are not considered as normal and usual in the human body. Cancer cells are example for abnormal cells. These </span><span><span>ignore normal laws of tissue boundaries and local territories. They cause problems to cells and organs crowd out other organs, take up space and prevent other critical functions from happening.</span> </span>
