Dogs are known for a strong sense of smell. Their noses can be trained to identify different smells. Dogs are often used in search and rescue operations and to sniff for things like drugs and explosives. Some dogs have even been trained to sniff for cancer in people. Researchers have been trying to reproduce the extraordinary sense of smell that real dogs are born with. Now, officials at the Glasgow airport in Scotland are testing a new security device called an "electronic sniffer dog". The electronic sniffer dog represents one of the latest developments in the area of smell technology. A Scottish company, Cascade Technologies, joined with the French security company Morpho to develop it. The device uses lasers to identify explosive materials in gases in the air. The purpose is to identify explosives that may be hidden on a person's body. The machine looks similar to the metal detectors now used at airports. Passengers walk through the machine as the lasers test the surrounding air. People are not required to take off their coats, belts or shoes as part of the security process. And, unlike full-body scanners, the new device does not show images of the passengers. Officials at Cascade Technologies say the machine can process one person per second and produce almost immediate results. They say future development could cut security processing times at airports by screening all passengers at walking speed. Professor Yushan Yan, the head of Chemical and Environmental Engineering at the University of California, Riverside, points out that unlike real dogs, electronic devices do not get tired or need to be walked or require food and water. Professor Yan says real dogs also have other needs. "They also need very extensive training that could be expensive. And when they work they have to have a very skilled handler around them." But Professor Yan says there is an important area where man's best friend still wins compared to technology. "In terms of sensitivity and selectivity, the current technology out there is still _ . The real dog has amazing capability of identifying some really minor amount of explosives." Which of the following is true of the electronic sniffer dog?
The device uses lasers to examine for explosive materials. People have to take off their clothes when walking through the device. The device will show images of the passengers. The device can process all passengers at walking speed.