Imagine living locked inside a closet. You can't choose when and what to eat or how you will spend your time. You can't even decide when the lights go on and off. Think about spending your whole life like this. This is the life of lab animals. Now consider the needs of these animals. Chimpanzees ,in their natural homes, are never separated from their families. They spend hours together every day. But in a lab, chimpanzees are put in cages alone. There are no families, only cold, hard cages, and loneliness that goes on for so many years that most of them lose their minds at last. Worse yet are the experiments. Animals are given diseases they would never normally get. Experimenters force-feed(......) chemicals to them, conduct repeated surgeries ,and much more, Think of what it would be like to put up with these and then be thrown back into a cage, usually without any painkillers. Often animals see other animals being killed right in front of them. Hundreds of thousands of animals are poisoned, blinded, and killed every year in product tests for shampoos, skin creams and new cancer drugs. Although more than 500 companies have stopped testing on animals, some of them still force chemicals into monkeys' stomachs and rabbits' eyes. Although some facilities are better than others at caring for animals--not every lab worker kills a mouse by cutting off its head with scissors--there are no happy animals inside laboratories. Will the lab life end? When will it end? We can infer from the passage that   _  .
some companies have found ways to replace animal tests animals normally get no strange diseases animals are happy in labs with better facilities painkillers can change the results of experiments