Hospital patients generally have lower infection rates and require shorter hospital stays if they are housed in private rooms rather than semiprivate rooms. Yet in Woodville' s hospital, which has only semiprivate rooms, infection rates and length of stays are typically the same as in several nearby hospitals where most of the rooms are private, even though patients served by these hospitals are very similar to those served by Woodville' s hospital. Which one of the following, if true, most helps to resolve the apparent conflict in the information above? ["Woodville's hospital has a policy of housing one patient per room in semiprivate rooms whenever possible.", 'Infection is more likely to be spread where people come into close contact with one another than where they do not.', "Most of the nearby hospitals were built within the last 10 years, whereas Woodville's hospital was built about 50 years ago.", "Many of the doctors who routinely treat patients in Woodville's hospital also routinely treat patients in one or more of the nearby hospitals."]