According to paragraph 2, astronomers most probably use...

Câu hỏi: Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.
Astronomers have long used direct photography to gather a large amount of information from telescopes.
To do this, they have special light-sensitive coatings on glass plates, whose size depends on the type of telescope employed. Certain wide-field telescopes commonly required very large glass plates. These plates do not bend, can be measured accurately, and can preserve information over a long period of time, providing a record that an astronomer at a later time can examine: However, even though long time exposures increase the amount of light striking the plate so that very faint objects in the sky eventually show up clearly, even the most sensitive plates convert only a small percent of the photons striking them into an image. For this reason, photography cannot make very efficient use of short time exposures on a telescope. Despite this inefficiency, photography is still very useful because it works as a two-dimensional detector covering a large area at a telescope's focus. Hence, the information contained in a single photograph can be enormous, especially when the photograph is taken with wide-field telescopes.
Today, the technology of newer radio and X-ray telescopes has allowed astronomers to view images otherwise invisible to the eye, and direct photography is now used less often to gather images. Today's astronomers can study an enhanced view of a telescope's focus on a television monitor; and in most cases, the data can later be converted by computer into digital form. This procedure, called image processing, plays a central role in astronomy today. Using false colors, the computer can display images of information otherwise undetectable to the unaided eye. These colors are false in the sense that they are not the actual colors of the object in the visual range of the spectrum. Rather, they are codes to a specific property, such as the X-ray emissions from stars.
According to paragraph 2, astronomers most probably use direct photography less often today than in the past because_______
A. photographic data deteriorates quickly
B. the technology of newer radio and X-ray telescopes has been developed
C. glass plates are no longer available
D. only a small amount of information is contained in a single photograph