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.
With focus on the subject matter, the reader is able to understand the main idea being described. Having a specific purpose for writing, defining the details, and then striving to stay on focus will help the audience determine its value to them. Readers are expecting some likely outcome to their lives when they pick up an article.