User: The greenhouse effect is a result of A. absorption and radiation of energy in the hydrosphere. B. consumption of fruits and vegetables that produce a biofuel. C. absorption and radiation of energy in the atmosphere.
A principal focus or focal point is a special focus: 1  For a lens, or a spherical or parabolic mirror, it is a point onto which collimated light parallel to the axis is focused. Since light can pass through a lens in either direction, a lens has two focal pointsâone on each side.
Pressure points are specific sensitive areas on the surface of the body. You can exploit a pressure point for many uses. Martial artists quickly disable attackers by using a simple but forced push on a pressure point. Stimulation of pressure points also helps to relieve pain and assists in massage therapy.