Colds occur frequently in autumn and winter, and tips for preventing colds have attracted much attention. It has been circulating on the Internet: placing an onion in the room can prevent colds, because the sulfur compounds volatile from onions have antibacterial and anti-cancer effects and can purify indoor air, Therefore, it is effective to prevent colds by putting a few onions with the cut ends in the room. If the following are true, which one can refute the above view? ['The sulfide contained in onion has a certain inhibitory effect on intestinal bacteria, but it needs to be taken orally a certain amount every day.', '0% -80% of colds in humans are caused by viruses, and onions have no inhibitory effect on the virus.', 'Experiments have shown that there is no significant reduction in the total number of bacteria in the room after the onion is placed in the room for 1 hour.', 'Existing research has not found that food can effectively adsorb bacteria and viruses.']