[单项选择] In this day and age of high-tech crime-solving methods, especially DNA typing, the lowly art of fingerprint identification sometimes seems lost. In fact, fingerprint evidence is highly reliable and particularly accessible to juries: You don’’t need a Ph.D. or a scientific lecture on genetics to understand that your own fingers contain a contour map of ridges and whorls that is completely unique. Matching Fingerprints Fingerprint evidence rests on two basic principles: A person’’s "friction ridge patterns" (the swirled skin on their fingertips) don’’t change. No two people have the same pattern of friction ridges. Police officers can use fingerprints to identify defendants and crime victims if a print matches one already on file. (Today, the FBI has a collection of prints that numbers in the millions.) People’’s fingerprints can be on file for a variety of reasons. For example, people may be fingerprinted when they are arrested, or when they begin certain occu
A. Only when people are arrested will their fingerprints be kept in the file.
B. In order to make fingerprints visible, you must use laser technology.
C. Even when the fingerprints found are incomplete, their whole patterns can be constructed with the help of computer.
D. Fingerprints won’’t be left on rough surfaces.