Question

Read the passage and answer the question. Passage: In the basement of the hospital stands a room that few visitors ever see: the medical records room. Row upon row of steel racks hold files tied with cotton tape, each one carrying the story of a patient who passed through the wards. A clerk in this room can find, within minutes, the file of a patient treated ten years ago, because every file is numbered, indexed and shelved in strict order. Now the hospital is moving these paper files onto computers. The change is slow work. Each page must be scanned, checked for clarity and given the same number as the paper file, so that a doctor searching for an old case can find it either on a rack or on a screen. Mistakes at this stage are costly: a wrong number can attach one patient's history to another, and a blurred scan can hide the very line a doctor needs. The staff therefore work in pairs, one scanning and one verifying, and the paper files are kept even after digitisation, in case the computer record is ever questioned. The room shows that in a hospital, the past is not thrown away; it is filed, numbered and kept ready for the day it is needed again. Why do the staff work in pairs during digitisation?