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.
1 emphasis is the visual amplification of areas in a work to draw more of a viewer's attention.  focal point is one area that has been emphasized to a greater extent than others in a work. Leonardo da Vinci's Last Supper uses linear perspective as a tool for creating a focal point in the center of the work.