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.
Social Sciences. Focus groups are a form of qualitative research that is commonly used in product marketing and marketing research, but it is a popular method within sociology as well. During a focus group, a group of individuals â usually 6-12 people â is brought together in a room to engage in a guided discussion of a topic.