The rat is named Lola and she's at the top of her class of risk-running animals being trained to smell out landmines   in Colombia, home to the world's highest number of mine-related deaths and injuries last year. Of the victims, many are children who died in _ while walking to school or playing in the countryside. The smartest rat among the first six that the government is teaching to locate landmines equipment planted by rebels  has a 90 percent success rate in locating landmines material in her lab training. Police animal trainers, tired of seeing their landmines-smelling dogs blown up by stepping on mines, hope the white-furred, pink-eyed creature will lead her classmates through coming open field tests and then into the country mine fields before the end of the year. It takes about 400 grams of pressure to detonate   a mine while Lola only weighs about 220 grams. "The dogs can easily set off the landmines, sometimes killing people nearby," they said. Police animal trainer Jose Pineda says that rats have more sensitive noses than dogs, which should allow them to better smell out mines in difficult terrain  . Plus, it takes the police about six months to train mine-smelling dogs. Training the rats is expected to take about half that time once the program is established. Trainers think that they are much smarter than the dogs. The second-best scorer in the laboratory is Lucrecia, with an 83 percent success rate. Males, such as one named   Runcho, have fallen behind until now but may do better in the coming field tests. Pineda said that the next step of training will present new challenges to the rats as they are sure to meet distractions   in the open. Which of the following is NOT a reason why rats are chosen to find buried landmines?
They have a good sense of smell. They are too light to set off buried landmines. They can smell all kinds of explosive materials. They cost people less time in terms of training