【单选题】

The human brain is hard-wired to recognize faces.But remembering faces is not the same as being able to describe them. This is particularly apparent when witnesses are asked by the police to create a composite picture of a suspect.Even when the result is thought to be a good likeness by the witness, that does not mean that other people will also be able to recognize the face and thus identify the suspect. The problem is that face recognition is a holistic (整体的) process: people are good at recognizing faces as a whole, but struggle to identify or describe individual facial features, such as a person’s eyes, nose or mouth.

But police forces inBritain and other countries are using a new technology that solves this problem by changing the task from one of recall into one of recognition. Instead of asking witnesses to select facial features, their system, calledEvoFIT, initially presents them with a grid (网络) of 18 randomly generated faces that match the race, gender and general shape of the suspect. From these the witness is asked to select the two that most resemble the suspect, however vaguely. The software then takes these two selections and "breeds" them, treating the facial features of their selections like genes, mixing them together and making random changes, to produce 18 new offspring which are displayed in a new griD、As this process is repeated, with the witness again choosing the closest two matches, the faces generated quickly converge (集合) on one that bears a resemblance to that of the suspect.
Dr. Frowd and Hancock, the researchers ofEvoFIT realized that if the results were to be improved further their evolutionary approach was not enough on its own. What was needed was a dash of psychology, because there are fundamental differences in the way people perceive familiar and unfamiliar faces, saysDr. FrowD、EvoFIT is now being used in practice. One of theBritish forces, theDerbyshireConstabulary, has now started usingEvoFIT exclusively. "It’s doubled our workload," saysBeverly Hunt, the force’s facial identification officer, because it is now possible to produce a useful image even when a witness has only a vague memory of a suspect’s face.
What is the problem of a witness when he is asked to create a composite picture of a suspect
A．It is easy for him to recognize faces as a whole.
B．He provides an incorrect picture of the suspect.
C．It is difficult for him to describe facial features.
D．He always cannot remember the suspect’s eyes.